Rev. Black has founded several community groups as well as the city's first black credit union. He also served as chairmen of the Social Actions Committee with the National Baptist Convention and president of the Baptist Minister's Union of San Antonio.
Rev Black was known throughout the South for his civil rights activism. Throughout the late 1950's and 1960's, he along with State Representative G J Sutton and Harry Burns were leading and organizing marches throughout the state. He challenged former Texas Governor Price Daniel, former San Antonio Mayor Walter McAllister and the establishment for their unfair treatment of minorities in the city. While addressing a city council meeting in 1952, he was ignored and called a "nigger" on the open mic. He became an associate of such leaders as A. Philip Randolph, Martin Luther King, Thurgood Marshall, Adam Clayton Powell Jr and others. He endured many threats to himself, his family and even his church. A drive-by shooting occurred on his home as well as his church was burned in 1974 with no suspects ever being charged.
He served four terms of the San Antonio City Council 1973-1978 and became the city's First Black Mayor Pro Tem.
San Antonio has a street, shopping plaza, and community center named in honor of Rev. Claude Black. The city of San Antonio has created the Rev. Claude & ZerNona Black Scholarship Endowment Fund.