Juvenile delinquency is an ongoing social problem particularly among low-income urban youth who are regularly exposed to numerous risk factors. Although much research has been conducted in this area, the most at-risk youth have been largely neglected. This study examines the role of peer deviance in mediating the influence of adult monitoring on male and female adolescents' delinquent behavior, using multisource, multimethod data with an emphasis on differing impacts across the two genders. Results suggest that the level of peer deviance partially mediates the impact of monitoring on delinquent behavior, even after controlling for previous levels of delinquency. However, girls' delinquency appear to be more influenced by peers than their perceptions of monitoring. Conversely, boys' delinquent behavior is associated with daily immediate monitoring, not peer behaviors. These results are discussed in the context of particular issues facing low-income urban African American families. (Contains 1 table and 4 figures.)