David Hackett, who led the Kennedy administration’s efforts to stem juvenile crime and helped create a domestic equivalent to the Peace Corps, died on April 23 in Rockville, Md. He was 84 and lived in Bethesda, Md.

Hackett, a close friend of Robert F. Kennedy’s since their prep school days at Milton Academy in Massachusetts, was executive director of the President’s Committee on Juvenile Delinquency and Youth Crime from 1961 to 1964. The committee was created by President John F. Kennedy in May 1961 after Hackett accompanied Robert Kennedy, then the attorney general, on a shirt-sleeve tour of poor New York neighborhoods, interviewing members of street gangs.

John F. Kennedy declared a five-year “total attack” on juvenile delinquency. With Hackett as director and an initial budget of $10 million, the committee provided grants to state, local and private agencies for programs offering counseling to juvenile offenders, connecting them to job opportunities and training youth counselors.

In an interview on Tuesday, Joseph P. Kennedy II, Robert Kennedy’s eldest son and a former Massachusetts congressman, said Hackett’s work had far-reaching impact.

“The outgrowth of that effort was the establishment of over a thousand agencies across the country,” Kennedy said. “Every major city and many rural communities now have community action agencies that began with the juvenile delinquency program and grew into the broader mission of fighting poverty.”

In 1962, Hackett was also chairman of a study group calling for the creation of a National Service Corps, a domestic version of the Peace Corps. That concept contributed to the establishment two years later of Volunteers in Service to America as part of President Lyndon B. Johnson’s war on poverty.

After leaving government service, Hackett was director of the R.F.K. Memorial, a nonprofit organization established after the assassination of Robert Kennedy, which focused on poverty and human rights issues. In that capacity he created the Youth Policy Institute, which tracked federal spending and policy on youth issues, family planning and job training and also published an influential monthly newsletter. It now runs more than 100 programs around the country, with the goal of lifting families out of poverty.