Kiss guitarist Ace Frehley was an actual member of The Ducky Boys gang. In his autobiography titled "No Regrets" he recounts his initiation and involvement with the Ducky Boys in his youth.
The gangs whose names are introduced early in the film (including The Wanderers) were based on real street gangs in the New York City area. However, they did not all exist at the same point in time. Many of the Wanderers did actually belong to a local football team, named "The Stingers".
The Ducky Boys, an actual Bronx gang that was portrayed in the movie, continued in existence through the 1970s. Though portrayed in the movie and Richard Price novel as "killers", neighborhood residents recall the gang as annoying rather than criminal.
Richard Price who wrote the novel which the movie was based from, picked all the songs in the soundtrack.