This paper examines Chicago's Forty-Two Gang. The Forty-Two Gang is one of the most famous groups in gang history, yet we know very little about the gang. Combining data from published and archival sources, this paper provides a history of the gang and explores its impact on the emergence of the Outfit, the traditional organized crime group in Chicago. The archival sources used in this analysis come from the unpublished John Landesco manuscript collection. The manuscripts not only provide a rich source of information on the Forty-Two Gang, but also a fresh look at the diffusion of delinquency subcultures and female participation in gang life during the early years of the twentieth century.