On March 22, 1947, one hundred civic leaders organized the Philadelphia Chapter of Americans for Democratic Action (now the Southeastern Pennsylvania Chapter) “to unite for common council and action progressive forces in the Philadelphia metropolitan area who are concerned with the preservation and extension of democracy.” National ADA had been formed on the previous January with many Philadelphia activists present. Nationally, progressive politics meant the extension of Franklin D. Roosevelt’s Four Freedoms, New Deal legislative program ADA, and anti-communist foreign policy. Locally, the Philadelphians were focused on municipal reform, but the Philadelphia ADA founders saw advantages in a national affiliation.

The early Philadelphia ADA leadership was unusual for its time in drawing from many backgrounds. Joseph Clark, Richardson Dilworth, and many others were Philadelphia “gentleman.” Others were civic leaders from prominent Jewish families. A third of the early boards came from leaders of labor movement organizations including the Congress of Industrial Organizations (CIO), the knit goods workers, the hosiery workers, the Steelworkers Union, the CIO Industrial Union Council, the International Ladies Garment Workers Union (ILGWU), and the Central Labor Union (CLU). The first permanent ADA executive director Harry Ferleger, came from the CLU. Other civic and social activists included John Patterson, chairman of the Public Education Association, Molly Yard Garrett, chairwoman of the American Students Union, and Leon Shull, who served as long-running executive director of both the Philadelphia chapter and national ADA.
In July, 1948, Philadelphia ADA hosted National ADA for the Democratic National Convention in Philadelphia. Against great resistance from Democratic leaders, ADA leaders fought successfully on the Convention floor for the adoption of the first civil rights in the history of the Democratic Party.