This article focuses on 58 Mexican American girls who were members of adolescent street gangs in East Los Angeles and who were heroin users. It examines the influences of family and subculture on whether the girls would be deviant mothers. Deviance was defined as using drugs during pregnancy or giving up a child. Four independent variables were considered: family of origin, discontinuity of social relations with family and with friends following heroin use, gender-role attitudes and exposure to deviant mothering which included the subject's age, number of children and immersion in heroin use. Different sets of factors were found to exist for the two types of deviant mothering. Approximately one-half of the girls were found to have used heroin during pregnancy and 40 percent gave up their babies. The girls who gave up their babies were more likely to have been raised in a traditional family and to have experienced estrangement or loss of contact with family and nonusing friends because of their heroin use. Older women, women with more than one child and the heaviest heroin users were most likely to give up a child. Women who gave up a child were more likely to have rejected traditional gender-role expectations. Those who used drugs during pregnancy were more likely than the abstainers to have come from "cholo" or underclass families in which some of the family's income came from illicit sources and one or more close family member was involved in a gang. These women were also likely to have been exposed to addicts during childhood and to be frequent runaways. They were more likely to believe that most Chicanos would reject a former drug addict. The implications of these findings are discussed. 1 table