Fresh from completing his medical residency at Yale-New Haven Hospital in 1964, Dr. Herbert Kleber fulfilled his military obligation by volunteering for the United States Public Health Service. He expected to do research at the National Institutes of Health. But to his dismay he was assigned instead to the Public Health Service Prison Hospital at Lexington, Ky.

This was the notorious “narcotics farm,” a centralized prison and drug treatment center where thousands of drug users were incarcerated at one time or another, including the actor Peter Lorre, the jazz trumpeter Chet Baker and the Beat writer William S. Burroughs, who described his experience there in his vivid novel “Junky” (1953).

Dr. Kleber fulfilled his two-year obligation in place of being drafted and returned to Yale, intent on a career in psychiatry. But because he had worked at Lexington, people assumed he knew all about addiction. After all, Lexington’s Addiction Research Center was an incubator for advanced research (and was the forerunner for the National Institute on Drug Abuse).

Patients, doctors and parents kept asking for his help. Finally, he gave in to what he decided was his destiny and, thanks to that unwanted detour to Lexington, went on to become one of the nation’s foremost experts in the field of drug addiction.

Dr. Kleber died on Oct. 5 while vacationing in Greece with his wife, Anne Burlock Lawver, his son, Marc, and his daughter-in-law, Judith. Marc Kleber confirmed the death and said his father, who lived in Manhattan, died of a heart attack on the island of Santorini. He was 84.

Dr. Kleber was a pioneer in researching the pathology of addiction and in developing treatments to help patients reduce the severe discomforts of withdrawal, avoid relapse and stay in recovery.

When he began his work, in the 1970s, health care professionals were paying little attention to addiction. It was a blip in the medical school curriculum.

Dr. Kleber helped elevate the study of addiction to a discipline, and over the course of his career the field attracted increasing clinical interest and research funding.

His focus was on so-called “evidence-based treatment,” in which professionals took a scientific approach to treatment in contrast to the punitive and moralistic approach that prevailed in the early days.

“He was at the vanguard of bringing scientific rigor to the area of addiction,” said Dr. Frances R. Levin, director of the division on substance use disorders at Columbia University Medical Center, a program started by Dr. Kleber.

“Things were actually tested,” Dr. Levin said. “There were placebo control trials. He wasn’t the only one, but he was among the first to give credibility to the field.”

His work at Yale, where he founded and headed the drug dependence unit, brought Dr. Kleber to the attention of President George H. W. Bush, who appointed him deputy to William J. Bennett, the nation’s first drug czar, in 1989. He left after two and a half years, frustrated that most of the billions of dollars earmarked for the nation’s unsuccessful “war on drugs” was still going to law enforcement and not to treatment.

“It reminds me of that cartoon,” he told The New York Times in 1992. “This king is slamming his fist on the table, saying, ‘If all my horses and all my men can’t put Humpty Dumpty together again, then what I need is more horses and more men.’ ”

At Columbia, he established the division on substance use disorder with his second wife, Marian Fischman, a prominent addiction research scientist, who died in 2001. It became one of the largest and most successful research programs of its kind in the country. At his death he was a professor of psychiatry there and emeritus director of the division.

He also co-founded the National Center on Addiction and Substance Abuse (now called the Center on Addiction) with Joseph Califano Jr., the former secretary of Health, Education and Welfare under President Jimmy Carter.

“His legacy,” Mr. Califano said in a statement, “will be the trained generations of professionals who will carry on his work and the thousands of lives that have been saved.”

Herbert David Kleber was born on June 19, 1934, in Pittsburgh to Dorothea (Schulman) and Max Kleber, both of whom were Eastern European Jewish immigrants. His father trained as a pharmacist before going into the family luggage business, “Kleber Trunk and Bag,” which manufactured soldiers’ footlockers during World War II. His mother raised bonds for the new state of Israel.

He attended Dartmouth College and Jefferson Medical College (now the Sidney Kimmel Medical College) in Philadelphia. In 1956, he married his high school sweetheart, Joan Fox, and they raised three children. The marriage ended in divorce.

In addition to Ms. Lawver, whom he married in 2004, and his son, Marc, Dr. Kleber is survived by two daughters, Elizabeth Kleber and Pamela Shad; six grandchildren; and one great-granddaughter.

His experience at Lexington had initially discouraged him about the prospect of treating addiction. While there, he learned that 90 percent of people relapse within three months of leaving treatment.

At that point, he said in 2015 in an oral history for Columbia, “the last thing in the world I wanted to do was to treat addiction.”

But, he said, “once you had been at Lexington, you were a marked man.” That is, everyone — “addicts who wanted help, doctors who wanted someone to refer to, parents worried about their children” — sought him out.

“Finally, after a year or so of that,” he recalled, “I said, ‘Well, maybe it’s fate.’ ”

Years later, during his Senate confirmation hearing to be deputy drug czar, he was asked how he kept up his optimism after so many decades of working with drug addicts.

Dr. Kleber responded with a paraphrase from the Talmud:

“The day is short. The task is difficult. It is not our duty to finish it, but we are forbidden not to try.”