Crime prevention from a developmental perspective is largely based on the idea that criminal activity is determined by behavioral and attitudinal patterns learned during an individual's development. Experiments have aimed to prevent criminal behavior or one of three important juvenile delinquency risk factors: socially disruptive behavior, cognitive deficits, and poor parenting. Experiments with juvenile delinquency as an outcome demonstrate that positive results are most likely when interventions target more than one risk factor, last for a relatively long period of time, and are implemented before adolescence. Experiments featuring early childhood interventions with socially disruptive behavior, cognitive deficits, or parenting as an outcome generally have positive effects. The majority of studies, whether small-scale confirmation or replication experiments, need to be followed by large-scale field experiments to test the efficacy and cost of developmental crime prevention in regular service systems. 183 references, 5 tables, and 3 figures