A study was designed to develop and validate a typology of leisure time activities using a scale called the Adolescent Leisure Time Activity Scale. In addition, the study examined the association between participation in the type of leisure activity and delinquent behavior among 2,651 middle and senior high school Mexican American adolescents of low socioeconomic status. A higher level of involvement in delinquency was significantly associated with increased participation in unsupervised socialization with friends and less frequent participation in organized leisure and sport activities and in activities at home. Different associations of leisure activities and delinquent acts were observed between males and females. Policy makers and community and school leaders should consider these and similar findings and focus their efforts on intervention and prevention strategies that nurture adolescent bonding to individuals and social institutions with conventional values and norms. In addition, parents should be made aware of the role of the home environment in protecting adolescents from delinquency. Tables, references