The respondents represented 97 percent of the 450 students who had received the questionnaire which included a list of 18 criminal acts. A total of 96 percent of the students reported committing 1 or more of the 18 crimes, and over one-third had engaged in 1 or more of the 5 more serious crimes: breaking into a building, stealing and selling property, stealing money using force, stealing something worth more than $50, and forcing someone to perform sexual acts. The crimes most often done as a member of a family group included vandalism (5 percent), obscene phone calls (3 percent), theft of less than $50 (6 percent), and forgery (6 percent). During the year they were high school seniors, about 6 percent of the students had committed a serious crime in collaboration with another family member. Assault was the most common serious crime by a family group. Siblings of the opposite sex and parents were involved in crimes with the sample members about as often as siblings of the same sex. Males in the sample had higher assault rates than females, but the sexes showed no important differences with respect to the other crimes. Family crime was not linked to socioeconomic status, although the families with low socioeconomic status were the only ones in which male criminality was greater than female criminality. Three tables, a footnote, and nine references are included.