A prevention trial was conducted to evaluate a temperament-based intervention (INSIGHTS into Children's Temperament) as compared to a Read Aloud attention control condition in reducing behavior problems among inner city children. The participants were 148 inner-city first and second grade children, their parents, and their 46 teachers who were from six schools in a Northeastern city. Parents were interviewed on the Parent Daily Report at baseline and every two weeks until the completion of the intervention phase to assess the extent of child problem behaviors in the home. The parents also were interviewed at baseline with the Disruptive Module of the Diagnostic Interview for Children and completed the Brief Symptom Index to assess parental depression.A repeated measures multivariate analysis of covariance with parental depression as a covariate was conducted to examine the children's behavior over the course of the intervention. In order to test the impact of INSIGHTS for the overall sample and to determine whether the intervention was differentially effective for children diagnosed with a disruptive disorder versus those who did not receive a diagnosis, two and three-way interactions were examined and found to be significant. The INSIGHTS intervention was more effective than Read Aloud in reducing children's problem behaviors at home across both the diagnosed and non-diagnosed groups, but demonstrated a significantly greater efficacy among children who were at diagnostic levels compared to those who were within normal levels. Editors' Strategic Implications: The authors describe the promising practice of instructing parents and teachers on how to adapt their behavior management strategies to fit each child's temperament. Replication with a longitudinal follow-up will be necessary to determine whether program effects persist.