Key Social Norms Take-aways This study shows that community-based voluntary counseling and testing (CBVCT) interventions can positively influence social norms around HIV testing. Community mobilization led to more favorable attitudes toward testing, particularly among men, by reducing stigma and encouraging open discussion. While stigma reduction was limited—possibly due to low baseline levels—the intervention succeeded in making HIV testing a more socially accepted and normative behavior in intervention communities. Objectives: To assess whether a community-based, multi-component HIV counseling and testing intervention could reduce HIV incidence and improve related behavioral and social outcomes compared to standard facility-based testing. Methods: A cluster-randomized trial was conducted across 48 communities in South Africa, Tanzania, Zimbabwe, and Thailand. Communities were paired and randomized to receive either 36 months of CBVCT or standard voluntary counseling and testing (SVCT). Data were collected through baseline and post-intervention cross-sectional surveys of 18–32-year-olds, using questionnaires and biological samples to assess HIV incidence and behavioral outcomes. Intervention Details: The CBVCT model included four components: (1) community mobilization to promote HIV testing and address stigma; (2) mobile HIV testing services; (3) post-test support groups; and (4) real-time performance monitoring. Services were available to all community members aged 16 and above. Results: HIV incidence was 13.9% lower in CBVCT communities compared to SVCT, though not statistically significant overall. A significant 30% reduction was observed among women aged 25–32. HIV testing uptake increased by 25%, including a 45% increase among men. Social norms around HIV testing improved by 6% overall, and by 8% among men. Among HIV-positive individuals, the number of sexual partners and rates of multiple partnerships declined. No significant changes were found in overall risk behavior, stigma, or HIV-related discussions. Conclusions: CBVCT can enhance HIV testing uptake and shift social norms, especially among men and older women. Though the reduction in HIV incidence was modest, the intervention demonstrates that combining community mobilization, accessible testing, and peer support can meaningfully influence behavior and norms. These findings support integrating social norm strategies into HIV prevention efforts to improve reach and impact.