To evaluate the feasibility and acceptability of a school-based intervention for diverse children exposed to a range of traumatic events, and to examine its effectiveness in improving symptoms of posttraumatic stress, depression, and anxiety. Participants were 74 schoolchildren (Grades 1–5) and their primary caregivers. All participating students endorsed clinically significant posttraumatic stress symptoms. School clinicians were trained to deliver Bounce Back, a 10-session cognitive–behavioral group intervention. Children were randomized to immediate or delayed (3-month waitlist) intervention. Parent-and child-report of posttraumatic stress and depression, and child report of anxiety symptoms, were assessed at baseline, 3 months, and 6 months. Bounce Back was implemented with excellent clinician fidelity. Compared with children in the delayed condition, children who received Bounce Back immediately demonstrated significantly greater improvements in parent-and child-reported posttraumatic stress and child-reported anxiety symptoms over the 3-month intervention. Upon receipt of the intervention, the delayed intervention group demonstrated significant improvements in parent-and child-reported posttraumatic stress, depression, and anxiety symptoms. The immediate treatment group maintained or showed continued gains in all symptom domains over the 3-month follow-up period (6-month assessment). Findings support the feasibility, acceptability, and effectiveness of the Bounce Back intervention as delivered by school-based clinicians for children with traumatic stress. Implications are discussed.(PsycInfo Database Record (c) 2021 APA, all rights reserved)