Objective: To evaluate a family- and church-based intervention for adolescents and caregivers in rural Kenya to improve family relationships, reduce HIV risk, and promote mental health. Method: The intervention was developed using community-based participatory methods and focused on strengthening family communication. Modules addressed economic, relationship, and HIV-related topics using evidence-based behavioral strategies alongside culturally grounded content. A stepped wedge cluster randomized trial was conducted with 124 families (237 adolescents ages 10 to 16; 203 caregivers) from 4 churches. Participants completed interviewer-administered surveys over 5 rounds. Primary outcomes included family communication, HIV risk knowledge, self-efficacy, and beliefs. Secondary outcomes included parenting, social support, mental health, and adolescent sexual behavior. We estimated intent-to-treat effects via ordinary least squares regression with clustered standard errors. Results: Relative to controls, the intervention group reported better family communication across domains at 1- and 3-months postintervention and higher self-efficacy for risk reduction skills and HIV-related knowledge at 1-month postintervention. Sexually active youth in the intervention reported fewer high-risk behaviors at 1-month postintervention, including unprotected sex or multiple partners. Male caregivers in the intervention reported higher parental involvement at both time points, and youth reported more social support from male caregivers at 3-months postintervention. No effects on secondary outcomes of parenting, social support, and mental health were detected. Conclusions: This intervention holds promise for strengthening positive family processes to protect against negative future outcomes for adolescents. Implementation with religious congregations may be a promising strategy for improving sustainability and scalability of interventions in low-resource settings.