Gerson M. Green, 70, the director of research and demonstration at the Office of Economic Opportunity from 1966 to 1969 and a lifelong advocate for disadvantaged sectors of society, died of a neurodegenerative disorder Dec. 5 at his home in Philadelphia.

At the OEO, Mr. Green helped oversee and implement the Harlem Commonwealth Council to promote black capitalism and Upward Bound to prepare poor children for college. He also focused on educational pilot programs on Indian reservations in 1968 and forming cooperatives among black farmers.

A Washington Post editorial in 1969 called Mr. Green "a creative and savvy official" whose "innovative and experimental programs have had positive effects in such fields as rural development, income maintenance, ghetto youth, community corporations, new towns for the poor."

Not all the programs were successes, the editorial noted, but it added that "all of it was high-risk where no federal programs had dared to venture before."

After leaving the OEO, he spent the next decade in Washington at several not-for-profit groups, including directing the National Neighborhood Institute of the National Center for Urban Ethnic Affairs from 1973 to 1978.

At the center, Mr. Green co-authored a 1976 study showing how Congress was "extremely unrepresentative" given America's ethnic and class demographics. The study said 75 percent of Americans had working-class backgrounds, compared with 22 percent of Congress, and concluded that the reason was the "low self-esteem" resulting from the lower strata's upbringing and social interaction.

From 1980 to 1992, he was executive director of neighborhood improvement agencies in Hartford, Conn., and Philadelphia.

He returned to Washington from 1993 to 1994 and was a regional director of the Corporation for National Service, where he administered the Americorps program in the southwestern United States. His illness cut short his time with the program.

Mr. Green was born in Arnold, Pa. He graduated in 1956 from the University of Pittsburgh, where he also received a master's degree in social work in 1961.

From 1952 to 1966, he was at several social service agencies in Pittsburgh.

He was a member of Americans for Democratic Action and volunteered in the Democratic presidential campaigns of John F. Kennedy and Lyndon B. Johnson.

Pablo Eisenberg, Mr. Green's deputy at OEO and a senior fellow at Georgetown University's public policy institute, said his former boss came to believe more could be accomplished through grass-roots nonprofit groups than in any level of government. There had been a backlash to the perception of big-government programs of the Great Society era, Eisenberg said: "People weren't sympathetic to poor people anymore."

Survivors include his wife of 42 years, Sharon Bramer Green of Philadelphia; three daughters, Antonia Green Bernstein of Washington, Lisa Green-Cudek of Baltimore and Lauren Green of Philadelphia; two brothers, Norman N. Green of Reston and Irving M. Green of Pittsburgh; and three grandchildren.