This study examines differential effects of the Cognitive Behavioral Intervention for Trauma in Schools (CBITS) program on behavioral and academic outcomes of middle school students. Researchers administered screenings to grade 6 students to assess traumatic stress and then randomized those with elevated levels to the CBITS treatment (n = 150; 47% female) or comparison group (n = 143; 53% female). Analyses examined the overall impact of CBITS and differential effects among subpopulations of students who reported clinically significant externalizing (n = 75; 67% female) or internalizing behavior (n = 185; 53% female) at baseline. Overall, students who received CBITS reported significantly reduced post-traumatic stress symptoms and marginally significant improvements in internalizing symptoms. Relative to counterparts in the comparison group, students exhibiting externalizing behaviors in the CBITS group reported significantly reduced post-traumatic stress, dissociation, anger, internalizing and total behavior problems, and also significantly improved scores on a standardized literacy assessment at posttest and follow-up. Students with internalizing behavior problems showed differential academic effects at 1-year follow-up; those in CBITS did significantly better on standardized math tests.