Analyzes the effectiveness of a cognitive-behavioral therapy (CBT) intervention to reduce symptoms of post-traumatic stress disorder (PTSD) and depression and improve psychosocial functioning and classroom behavior in students. Study participants in this fully randomized clinical trial were approximately 100 sixth-grade students attending 2 large urban middle schools in a largely Latino area of Los Angeles, California. Participants attended 10 therapy sessions as part of either an early-intervention or a delayed-intervention group. The Cognitive-Behavioral Intervention for Trauma in Schools (CBITS) incorporates CBT skills in a group format and emphasizes applying techniques addressing symptoms of PTSD, anxiety, and depression related to exposure to violence to a child’s own problems. At the 3-month mark, students in the early-intervention group had significantly lower self-reported symptoms of PTSD and depression than did the students in the delayed group, although at the 6-month mark, after the second group had completed the CBITS sessions, this difference disappeared. Teachers, however, did not report significant improvements in classroom behavior in either group, which may suggest that there is a lag time before children’s symptomatic improvement translates into improved behavior. Nevertheless, the study demonstrates that a carefully implemented, community-based intervention can significantly reduce PTSD symptoms in the short term.