Five types of problem behavior were investigated for adolescent boys and girls: delinquency and the use of tobacco, alcohol, marijuana, and other illegal drugs. The relations between risk, protection, and each form of adolescent deviance were examined over a 1 year period. Survey data were collected in nine high schools in California and Wisconsin from the fall of 1987 through the spring of 1990. Two questionnaires per school year were given to students. Approximately 80 percent of the students in each school participated. Results showed that, contrary to expectations, the gender groups did not differ markedly in their level of risk. Boys had more delinquent friends, but the friendship groups of boys and girls did not differ significantly in the use of tobacco, alcohol, marijuana, or other drugs. As expected, boys and girls differed in their levels of protection and deviance. Adolescents who had positive relations with parents and teachers and who had strong commitments to achievement generally exhibited fewer behavioral problems. In general, school factors were consistently more protective among boys and girls than were family factors. Family factors had few consistent effects on adolescent friendships and behavior, and occasionally increased adolescent vulnerability to negative friendship environments. The use of a longitudinal design and the use of actual reports by friends increase confidence in the conclusion that various individual and interpersonal factors related to the family and the school can reduce deviance and the influence of deviant friends for both adolescent boys and girls. 3 figures, 4 tables, 66 references