Sgt. Jeffrey Beltran pulled a heavily creased Post-it note from the pocket of his fatigues, unfolded it and looked over a list he jotted down earlier that day: pick up an order of beef lo mein, take his dress uniform to work (jacket, pants and boots), do schoolwork. Beltran’s Army-issue organizer is also filled with these reminders, and he checks them every so often to jog his memory — folding and unfolding them throughout the day. Beltran’s life is filled with sticky notes because his short-term memory is no longer reliable, a result of what the Army calls a mild traumatic brain injury <>  that he suffered in an I.E.D. attack in Iraq in 2005.

“I have pictures,” said Beltran, who is 44, as he pulled a worn Ziploc bag from his backpack and removed a half a dozen photographs. He began laying the images on his desk. “We were turning our vehicle around when we got hit.”

The photos, taken right after the explosion, show a plowed field next to a road. A few palm trees frame the horizon. In the foreground there is a deep crater. About 20 feet away, the front half of a Humvee is turned upside down. The back half is gone — parts were later discovered hundreds of feet away. When the bomb exploded, Beltran was launched into the air and landed between the blast hole and the Humvee. When he came to, he couldn’t stand up. “I knew something was wrong,” he said. “I felt swelling inside my legs. I was hyperventilating in the heat. The dirt was starting to settle down. I called out to my guys. I couldn’t see them.”

The blast broke Beltran’s knee and leg, fractured his lower spine and buried shrapnel in his thigh; the violent jolt caused his brain injury. He suffered so many wounds that he had to pause in the retelling to make sure he hadn’t left anything out. He underwent 14 operations over the next year. “I was dealing with post-traumatic stress, anger, all the emotions, the ups and downs, the physical, emotional, psychological pain,” he told me. “I was really angry. I wanted to get healed and get back into the fight.”

By 2007, Beltran was on several medications: Clonazepam and Buspirone for anxiety, Celebrex <>  for pain and other pills for depression. Yet the Army deployed him again, this time to Bagram <>  Airfield in Afghanistan, where he coordinated with nongovernmental organizations to clear minefields. He saw a farmer blown up. A soldier he worked with closely was killed. Whenever a soldier died, a memorial service was announced over the public address system, and the base’s main road was shut down for the soldier’s final ride to the mortuary. “That wears on you,” Beltran said. “As much as you want to avoid it, death is always in front of you.”

After six months in Afghanistan, Beltran was given a diagnosis of post-traumatic stress disorder and sent home. The Army offered him a medical discharge, but he declined. Beltran’s father served 21 years in the Navy, and his grandfather survived the Bataan death march. So despite all the troubles that followed — he was even hospitalized after considering suicide — he stayed in the Army.

Slowly, though, Beltran began noticing surprising changes. Before the blast, he drifted. He spent a lot of his free time playing video games. Like many soldiers, he was more concerned with figuring out how to cope from one deployment to the next than with finding a direction. He is different now. The bombing, the P.T.S.D. and the challenges he faced changed him. And he thinks he has changed for the better. “This whole experience has helped me to be more open, more flexible,” he told me. “I am branching out to activities that I was once uncomfortable with.” Beltran has taken rigorous tests in pursuit of a promotion. He’s taking online courses toward a bachelor’s degree in criminal justice. He discovered a sense of spirituality, and although he and his first wife divorced, he has remarried and reconnected with his parents, from whom he distanced himself after the explosion.

Beltran spent years in therapy and read many books about people who surmounted adversity, all of which, he says, helped him change. More recently, through classes and group therapy at Fort Sill in Oklahoma, he was introduced to the science and thinking behind this psychological change. “It’s given it a name,” Beltran said, “and has enhanced my personal development.” The name for Beltran’s change is post-traumatic growth. And the classes he takes are part of a $125 million Army-wide program called Comprehensive Soldier Fitness, which is intended to help soldiers become more resilient and to help them recognize how the trauma of combat can change them for the better. For years, Beltran carried photos of the explosion to remind himself of what he overcame. Now, he says, he carries those pictures to show to others. “I want to share my experience,” he told me. “Whatever knowledge or wisdom I have.”

The idea that people grow in positive ways from hardship is so embedded in our culture that few researchers even noticed that it was there to be studied. Richard Tedeschi, a psychologist at the University of North Carolina, Charlotte, who is both a researcher and a clinician, discovered it in a roundabout way, while he was looking for a new research project. “I thought, Who do I want to know the most about, distressed or violent or crazy people?” he told me. “Instead, I think I want to know about wise people. Perhaps I’ll learn something myself.” He and Lawrence Calhoun, who is also a psychologist at U.N.C., started their research by interviewing survivors of severe injuries. He then went on to survey older people who had lost their spouses. Person after person told them the same thing: they wished deeply that they had not lost a spouse or been paralyzed, but nonetheless, the experience changed them for the better.

Patterns began to emerge in a follow-up study of more than 600 trauma survivors. People reported positive change in five areas: they had a renewed appreciation for life; they found new possibilities for themselves; they felt more personal strength; their relationships improved; and they felt spiritually more satisfied. Tedeschi developed an inventory to track and measure the phenomenon, and in 1995, he and Calhoun coined the term “post-traumatic growth.” Experiencing growth in the wake of trauma, Tedeschi asserts, is far more common than P.T.S.D. and can even coexist with it.

Since P.T.S.D. was accepted as a legitimate condition five years after the end of the Vietnam War, the military has put vast resources into coping with it. The Department of Veterans Affairs spent more than $5 billion on mental-health services last year. Soldiers are screened for P.T.S.D. symptoms after deployment, and chaplains, social workers and psychologists are trained to spot them. The disorder combines anxiety and an inability to regulate the fear response. For some, the symptoms never completely abate. These soldiers often relive their traumatic experiences over and over. They have trouble sleeping. They are always on hyper-alert. In 2010, the Army gave a diagnosis of post-traumatic stress disorder to 10,756 troops, up from 4,967 in 2005.

With so much attention, understandably, on the disorder, few researchers have asked soldiers about positive changes they might have experienced. The ones that did found startling results. One of the first studies, published in 1980, was conducted on aviators captured during the Vietnam War. It reported that 61 percent said they had benefited psychologically from their experience of captivity. The airmen foreshadowed the themes that would later become the foundation of Tedeschi’s work. Many said that they had stronger religious convictions and enjoyed life more. They said they appreciated others more. Those treated most harshly by their captors reported the most positive change. Perhaps it was no more than the desire to give meaning to a horrible time in their lives, but a follow-up study conducted 25 years later found that the soldiers remained convinced that the captivity had changed them for the better.

Last spring, Tedeschi was in Wilmington, N.C., to speak to about 150 veterans, military family members and social workers. He is a tall, wiry man with deep-set eyes and a soft, even voice. After his presentation, we had lunch in the student snack bar, where he explained the dynamics of post-traumatic growth. Only a seismic event — not just an upsetting experience — can lead to this kind of growth. By that Tedeschi means an event that shakes you to your core and causes you to question your fundamental assumptions about the world. Survivors of such severe trauma inevitably confront questions about existence that most of us avoid, and the potential for growth comes not from the event itself but from the struggle to make sense of it. Tedeschi calls this rumination, and he argues that it can happen alongside P.T.S.D., after P.T.S.D. or in its absence. “The challenge is to see the opportunities presented by this earthquake,” Tedeschi says. “Don’t just rebuild the same crappy building you had before. Why not build something better?”

On a late spring morning, 180 soldiers gathered in the basement of a Sheraton hotel in Philadelphia. Most were sergeants who had completed at least one combat deployment. Decked out in camouflage and desert boots, they were attending a 10-day Master Resilience Trainer course meant to help create a more psychologically fit army.

The Army’s resilience training program was shepherded by Brig. Gen. Rhonda Cornum. She is a physician, a pilot and a competitive horseback rider. She was also a prisoner of war. In the first gulf war, Cornum, then a flight surgeon on a Black Hawk helicopter, was shot down during a rescue mission. She woke pinned to the ground by wreckage. She had two broken arms and was held prisoner for eight days. In her book about the experience, “She Went to War,” Cornum comes off as someone with an indomitable sense of optimism.

“I was badly injured, but I knew that I would heal eventually,” she writes. “The crash had been so devastating that I should have died then, and I regarded every minute I was alive as a gift. The Iraqis could have killed us easily when they found us at the crash site, but they chose not to. Then in the circle of men a slight pressure on a single trigger would have been enough to kill us, but we had been spared. It was just good-enough luck for me to grab onto and to hold. I vowed to survive.”

When I visited Cornum, who recently retired, in Virginia, and suggested that most people would be hard-pressed to find anything resembling luck in that situation, she laughed, acknowledging the absurdity, but then she said: “It’s the only way I would think. I’ve been practicing that my whole life. If you don’t do that, why would you ever proceed with anything?”

When she returned home, people expected to hear anguished tales, but she had none to report. In fact, she could come up with only positive things to say. She now empathized more with her patients because she had been one; she became closer to her family and a more self-confident leader. In 2006 she came across an article about Tedeschi’s work, and she found a way to think about — and name — her own experience.

At the time, Cornum wanted to develop a psychological training program for the Army. In her view, today’s soldiers are in dire need of toughening up. “This is the trophy generation,” she said. “Kids are taken places to participate in carefully orchestrated activities where no one is allowed to lose or have a fight.” Those people may have trouble adjusting to the hardships and violence of war. “We have really sanitized death,” she says. “They go to Iraq and Afghanistan, and it is not sanitary anymore.”

Cornum’s efforts did not gain traction, however, until 2008, when the Army’s chief of staff, Gen. George W. Casey Jr., got behind the idea. Cornum met with Martin Seligman, a professor at the University of Pennsylvania, a giant in the field of positive psychology, who developed a program to help adolescents perform better in school. Cornum worked with him to set up a series of meetings with experts in resilience, positive psychology and growth. Then, largely under Seligman’s guidance, the Comprehensive Soldier Fitness program came into shape.

In less than two years — without a single pilot or study — the program has been rolled out to the Army’s one million solders. Every soldier takes the General Assessment Tool, a 105-question survey, which asks soldiers to respond to statements like, “In uncertain times I usually expect the best” (Cornum would score high on this), or “If something can go wrong for me, it usually will.” Depending on how soldiers score, they are prompted to complete online training in any of the program’s five key areas: physical, emotional, social, family and spiritual (which could mean either religious faith or personal reflection). The Master Resilience Trainer program, part of this larger effort, is supposed to turn the noncommissioned officers closest to young soldiers into teachers of positive psychology.

A week into the training course at the Sheraton in Philadelphia, the soldiers were divided into groups for role-playing exercises to help develop techniques for optimistic thinking. I sat at a round table in a small basement meeting room with eight soldiers who had been given the following situation: You are the sergeant in charge of a unit, and a soldier shows up late for early-morning formation twice in a row. The group had to come up with a worst-case scenario, a best case-scenario and what was most likely to happen.

Sitting at the table was Sgt. First Class Chris Tweedell. An Oliver Stone vision of a sergeant — towering, broad and topped with a pale shaved head — Tweedell is blessed with a deep, powerful voice. Tweedell and the other sergeants were supposed to be learning how to train others to avoid catastrophic thinking. But trying to dream up optimistic outcomes for the hypothetical situation was exasperating him. “That is why I hate this stuff,” he said, dropping his head in his hands. Seligman’s work suggests that if people take the time to come up with these three possible outcomes, it allows them to assess their reaction to a situation more clearly. That does not mean that every outcome is going to be positive — in many cases, in war especially, something bad is going to happen.

Tweedell served in Iraq in 2003 and 2004 and completed two tours in Afghanistan. When he returned from his first deployment, his home was broken into. He got divorced. He remarried, but coming home from tours continues to be hard. “There are highs and lows, and you don’t know if it is your own mood or sleep deprivation or road rage,” he says. “I’ve had a few episodes of P.T.S.D.” Optimistic possibilities were not coming to him easily. (Tweedell’s group eventually came up with this best-case ending: the soldier would get mentoring. The more realistic outcome: he would be put on an unpleasant work detail.)

Some studies show that optimism is linked to increased resilience and to the likelihood of psychological growth. But it’s not clear what comes first — does optimism lead to resilience or the other way around, or are both true? Seligman’s theory is that if soldiers can be taught to approach a situation as General Cornum did naturally — with gratitude for being alive rather than distress at being taken prisoner — then they might learn to become resilient, too. A core principle of the program is seeing an event as neutral, neither bad nor good, and focusing instead on your reaction to the event. One exercise many soldiers told me they like suggests that they “hunt the good stuff” by writing down three good things that happened during the day before they go to sleep each night.

A week into the training, I met with Tweedell for a second time. Despite his groaning over the exercise, he was excited about the goals of Seligman’s course. “This is a holistic view of a total soldier: mind, body, soul — a supersoldier,” he told me. “Someone has finally understood that we need to be mentally tough.” He told me that the course was making him think about how he communicates with peers, not to mention his preteen stepdaughter. Seligman encourages soldiers to communicate in what he calls an active, constructive way — drawing out others, encouraging detailed discussions of positive events. Tweedell was realizing that he often avoids conversation with his stepdaughter because he assumes she does not want to talk to him. “How often do I ask her what good things happened to her today?” he said. He told me that as a soldier, he often communicates passively as well. “Maybe this is why I have the relationships that I have at home at and at work,” he said.

It’s not a big leap to imagine that Seligman’s tools could improve family or work communication. But can positive thinking really protect against the harsh experiences of war? Soldiers’ experiences are unique. They develop intense bonds with one another, and all too often they see those closest to them die. Relentless boredom is punctuated by moments of pure terror. Young men and women who have little experience with mortality are suddenly confronted with gruesome scenes of death. Some grapple for years with the emotional complexities of killing and watching people die. “These programs were designed to make people happier and healthier,” says George Bonanno, a professor at Columbia University who studies trauma and resilience. “That is not the same thing as inoculating people for serious urinate-in-your-clothing type stress — once-in-a-lifetime stress.”

Brett Litz, a professor at Boston University School of Medicine and a clinical psychologist at the V.A. Boston Healthcare System, says that there is little evidence that prevention aimed at healthy people — as the Army’s is — has any impact on the onset of P.T.S.D. “Whether this program can help servicemembers when they are in the hell of war faced with trauma and loss and the grotesque aspects of war, that is unclear,” he says.

We may never know how effective it is because the program, which costs about $125 million over five years, was designed for quick implementation, not research. General Cornum originally planned to pilot a few psychological training approaches so they could be studied against a control group of soldiers who received no training at all. But that would have taken years, and General Casey wanted the program rolled out right away to everyone. The Army is conducting studies — comparing four brigades that have resilience trainers with four that do not — and in December it released the first results, which found small improvements in emotional and social fitness and a small decrease in catastrophic thinking among those soldiers whose brigades had trainers over a six-month period. Capt. Paul Lester, the lead researcher, says that future studies will look at disciplinary problems, illness and other more objective measures. He argues that this initial study points to the effectiveness of the program, saying that small changes in such a large group — there were 22,000 surveyed — are important indicators. But he also admits that the study is imperfect. Some brigades have deployed to combat and some have not; the individual soldiers have varying levels and types of military experience; all the subjects have taken the Army’s resiliency survey; and the change is entirely self-reported.

The true test of the program is how it works in combat. Last year, resilience trainers were assigned to the Second Stryker Cavalry regiment in Afghanistan, in which Pvt. First Class Brian Hinkley served. Hinkley told me that children in villages would throw rocks at the soldiers or spit at them. But advice from his resilience trainer helped him to “hunt the good stuff” and focus on the exceptions. “The few people that invite you in and offer you bread and chai, they make up for the 50 that throw rocks at you and want to blow you up,” Hinkley told me. His trainer was not trying to instill false optimism but rather a better way of dealing with inevitable hardship. “He told us there were going to be bad days, but also how to deal with it in a positive way,” Hinkley says. Hinkley’s story is just an anecdote. And while he found the training valuable in the stressful situations he was in, he doesn’t know if it would have made a difference on a violent battlefield. And Hinkley might well have responded this way naturally, like Cornum. But now, at least, he had a conscious frame for his response.

The traditional view of trauma was bifurcated: you either got P.T.S.D. or you were fine. Researchers today have a messier perspective. It is normal to have problems following trauma. You should lose sleep, have terrible images replay in your head, be racked by guilt or fear. Some people suffer these normal post-trauma reactions to one degree or another and recover, returning to a relatively normal state within weeks or months of the event. Others appear unchanged at first, only to react months or even years later. The majority of these people also recover. (Bonanno, the critic of the Army’s program, says his recent study found that most soldiers are already remarkably resilient — 85 percent of them having no lasting adverse reaction from combat.) A small percentage of people get trapped in their trauma and experience P.T.S.D. Tedeschi and others say that the majority of people across this entire spectrum also grow as a result of their suffering. Paradoxically, many grow even as they suffer. The way we cope with trauma is far more complex than once thought, and the way it molds us is similarly complex. We bend, we break, we repair and rebuild, and often we grow, changing for the better in ways we never would have if we had not suffered.

Researchers have found evidence of post-traumatic growth in cultures across the globe. Tzipi Weiss is an associate professor of social work at Long Island University’s C.W. Post Campus and an author of “Post-Traumatic Growth and Culturally Competent Practice.” She found studies that reported post-traumatic growth in Israelis who survived terrorist attacks and in Palestinians who were held in Israeli prisons; in Turkish earthquake survivors and Germans who survived the Dresden bombing. In her own research, Weiss found growth in the spouses of cancer survivors. “It’s pretty clear that post-traumatic growth is a universal phenomenon,” she says.

But growth is not a given. Not everyone climbs out of despair changed for the better. An overreliance on drugs to treat P.T.S.D., some clinicians argue, might even stifle growth. Pamela Fischer, director of primary care mental health at the Oklahoma City Veterans Administration Medical Center, spent a dozen years working in the P.T.S.D. unit there and cites studies suggesting that some continuing distress from P.T.S.D. is necessary for growth to occur. Doctors should not take medication away from patients, she says, but they can encourage them to work through the pain, to see it as a motivation. As Weiss puts it, “Pain and suffering are the mechanisms for growth.”

When it comes to treatment, however, there isn’t a consensus on how, or whether, to integrate the concept of growth. Patricia Watson, a senior education specialist for the National Center for P.T.S.D., says studies indicate that pushing people toward growth can be ineffective, making patients believe that they need to be strong even when they are in mental agony. Rachel Yehuda, director of the Traumatic Stress Studies Division at Mount Sinai School of Medicine, says that timing is crucial. Bringing up the idea of growth before patients have completed therapy — which often involves what is called “prolonged exposure,” or talking through the trauma in detail again and again to help patients overcome their fear of the event — might not be “a therapeutic thing to say to someone who is suffering,” she says. “I don’t reject the idea; I just want to be careful to do it right.”

Many of the V.A. psychologists I spoke with were familiar with the idea of post-traumatic growth — some have even done research on the subject — yet not all of them have used it in therapy, and the V.A. has no official policy on it. Social workers at Fort Sill, however, introduce the idea of growth right away, though as a long-term objective. When soldiers come in shattered by a traumatic experience, social workers explain that they will lose sleep, be angry, upset and depressed, and that these are normal reactions. But they also tell them that there is a chance that, given time, they may be stronger as a result of what they went through.

Some academics question whether post-traumatic growth is a real phenomenon, or at least one that can be objectively defined. Nearly all studies ask people to look back and recount how an event changed them. In the wake of trauma, people might tell themselves that they changed for the better, if only as a way of making some sense of a senseless tragedy. As far as friends and spouses are concerned, however, the person might have not changed at all. “I have no doubt that there are people, perhaps many people, who do change in positive ways, but we are not able to measure it,” says Howard Tennen, a professor of community medicine and health care at the University of Connecticut. And if you can’t measure it, Tennen says, then you really have no business trying to promote it.

Tedeschi would love to see better studies. But he also is adamant that the phenomenon is real and can be measured, even if researchers must rely on self-reported, after-the-fact accounts. “Virtually all psychological research relies on memory,” he told me. “If you decide that memory is unreliable, then you have to throw out everything that has ever been published in psychology.”

Tedeschi told me about one of his patients whose helicopter was shot down in Vietnam. As he fell from the sky in the midst of gunfire and explosions, a peace came over him. He saw the jungle around him, and it was beautiful. He felt connected to everyone, even enemy soldiers. Since then he has reflected on the experience, delving into philosophy and religion. He has reached out to others by volunteering his time. He has tried to remain true to that connection he felt long ago. “Maybe that was all an illusion,” Tedeschi says. “But that became a guideline for his life, so I don’t think you can dismiss it. People can have profound personal experiences that directly change their perception and philosophy. That may show up in the things they do, but it also may not.”

For most people, change does not occur in a transcendent moment but over years of prosaic searching. That was the case for Sergeant Beltran, whose Humvee was blown apart by the I.E.D. in Iraq. Rebuilding his life was a struggle, but over time he became a trainer in the Comprehensive Soldier Fitness program at Fort Sill and now is working at Fort Stewart, in Georgia, where he and his new wife, Ronda Jones-Beltran, have bought a house. “Instead of labeling myself as a P.T.S.D. veteran, I say that I am a post-traumatic-growth veteran,” he told me. “I am a person looking forward.”