Conflict-affected youth are at risk for poor psychological and social outcomes, yet few receive mental health services. Strategies to expand access and sustain evidence-based interventions (EBIs) across novel delivery platforms must be tested. The present study was a hybrid type II implementation-effectiveness trial using a cluster randomized design. The primary goal was to evaluate feasibility and impact of using the collaborative team approach to deliver the Youth Readiness Intervention (YRI), an EBI, integrated into a youth entrepreneurship program (ENTR) with quality control in post-conflict Sierra Leone. Youth were screened and randomly assigned to control, ENTR, or combined YRI and ENTR (YRI+ENTR). Implementation outcomes were dissemination and implementation indicators, competence, and fidelity. Effectiveness outcomes were emotion regulation, psychological distress, and interpersonal functioning. Secondary outcomes were third-party reporter assessments of youth functioning and behavior. Data were collected and analyzed from 1,151 youth participants and 528 third-party reporters. Scores on implementation constructs, competence, and fidelity demonstrated acceptable intervention response and quality. YRI+ENTR participants showed overall improvements in depression (β=-.081, 95% CI-0.124 to-0.038, d=-0.154) and anxiety (β=-.043, 95% CI-0.091 to-0.005, d= 0.082) symptoms compared with control participants. Community leaders indicated that YRI+ENTR participants demonstrated improvements in overall work or training performance compared with control participants (β=-.114, 95% CI 0.004 to 0.232, d= 0.374). Integration of EBIs such as the YRI into youth employment programs has the potential to address limited reach of EBIs in conflict and post-conflict settings. A collaborative team implementation approach can facilitate integration and fidelity. In a Hybrid Type-II Implementation-Effectiveness trial conducted in Sierra Leone, researchers tested a Collaborative Team Approach (CTA) for delivering an evidence-based mental health intervention, the Youth Readiness Intervention (YRI), within a youth entrepreneurship program. A total of 1,151 youth participated in the study, with outcomes measured on youth mental health indicators of emotional regulation, psychological distress, and interpersonal functioning, as well as implementation indicators, competence, and fidelity. Results demonstrated that the integrated YRI and entrepreneurship program led to significant improvements in depression and anxiety symptoms compared to the control group. Community leaders also noted enhanced overall performance in YRI participants, suggesting that integrating evidence-based interventions into youth employment programs can effectively address mental health challenges in low-resource regions. We worked to ensure sex and gender balance in the recruitment of human participants. We worked to ensure that the study questionnaires were prepared in an inclusive way. We worked to ensure race, ethnic, and/or other types of diversity in the recruitment of human participants. One or more of the authors of this paper self-identifies as a member of one or more historically underrepresented racial and/or ethnic groups in science. One or more of the authors of this paper self-identifies as a member of one or more historically underrepresented sexual and/or gender groups in science. We actively worked to promote sex and gender balance in our author group. We actively worked to promote inclusion of historically underrepresented racial and/or ethnic groups in science in our author group. The author list of this paper includes contributors from the location and/or community where the research was conducted who participated in the data collection, design, analysis, and/or interpretation of the work. One or more of the authors of this paper received support from a program designed to increase minority representation in science. Youth FORWARD Phase 2 YRI and EPP Study; https://clinicaltrials.gov/; NCT03542500. Youth Functioning and Organizational Success for West African Regional Development (Youth FORWARD): Study Protocol; https://doi.org/10.1176/appi.ps.202000009.