The Delancey Street Foundation, often simply referred to as Delancey Street, is a nonprofit organization based in San Francisco that provides residential rehabilitation services and vocational training programs for substance abusers and convicted criminals. It operates programs across the United States. Residents are reintegrated into mainstream society by running various businesses, including hospitality, transportation, and retail, that are wholly managed by the residents themselves.

Delancey Street Foundation was founded in 1971 in San Francisco by John Maher. The program began in an apartment on Polk Street that Maher, a self-described "bum" and "ex-junkie", rented to house people recovering from drug and alcohol use. As the number of people at the apartment increased, the group pooled funds to expand and formalize the organization, initially called Ellis Island and then renamed Delancey Street. It was named after Delancey Street on the Lower East Side of Manhattan, a settling place for immigrants at the turn of the 20th century. According to Maher, "We wanted to get back to the concept of a bunch of wild-eyed fanatics who came over here to build a New Jerusalem and not ask Uncle Nixon for another handout."

Maher was a former member of Synanon, which he had joined in 1962. Delancey Street drew inspiration and methods from Synanon, including the "Game" method of intense, confrontational group therapy; though Mimi Silbert later disavowed any relationship or influence between the two organizations.

Maher could not acquire a loan from a bank. For this reason, he borrowed one thousand dollars from a loan shark for startup funds. The first location was in a Bush Street apartment, but Maher eventually raised enough money to rent the Egyptian Consulate building in the affluent Pacific Heights neighborhood. When neighbors discovered there was a re-educational environment in the neighborhood, several formed a committee to have Delancey Street evicted. Within a year of its founding, the Delancey Street community had grown to 100 members.

Maher met Mimi Silbert, a Boston-bred criminologist and psychologist from UC Berkeley. Silbert began helping Maher structure the foundation. Maher and Silbert also became romantically involved.

In 1974, Delancey Street was instrumental in gaining the release from prison of Wesley Robert Wells. Wells went into the prison system at 19 years of age. By 1974, he had been incarcerated for 46 years, longer than anyone in California. Seven of those years were on Death Row in San Quentin State Prison. The campaign slogan was, "46 Years is Enough." Wells was paroled into the custody of Delancey Street, where he became a resident, and died a year later of natural causes.

In the 1970s, Maher and the foundation became closely linked with Cesar Chavez and his organization, the United Farm Workers. In 1975, Delancey residents worked as part of Cesar Chavez's personal security team, marching in the "Thousand Mile March", culminating in the Farm Workers' convention, where Maher gave a speech.^{[citation needed]}

Maher became friends with one of San Francisco's renowned artists, Dugald Stermer, art director for Ramparts magazine. Dugald became a print media advisor and eventually a councilor, and moved his studio to Delancey Street's Embarcadero Triangle complex. Dugald was involved until his death in 2012. Another Bay Area notable, KSAN-FM radio jock Stefan Ponek, joined Delancey's board of directors. Bill Maher, John's younger brother, who was a resident, graduated from law school, ran for and won the presidency of San Francisco's school board, and then was elected to the San Francisco Board of Supervisors.