BACKGROUND: Young men who have sex with men (YMSM), particularly those who are partnered, are at unique risk for HIV. YMSM are among those at highest risk for HIV. Meanwhile, despite the fact that primary partners account for many-possibly most-new HIV infections, partnered men who have sex with men perceive themselves to be at much lower risk for HIV infection and therefore test less often than single men. In response to the risk of primary partner HIV transmission, couples HIV testing and counseling (CHTC) procedures have been developed for use in adult populations. Although promising, YMSM couples may require additional support to complete CHTC given their developmental context in which sexual and romantic relationships are relatively new, and communication skills are emergent. OBJECTIVE: The aim of this study was to test the additive benefit of adjunct treatment components tailored for YMSM, which enhance communication skills before the completion of CHTC. The intervention tests a continuum of prevention packages including assertive communication training videos and motivational interviewing focused on assisting with identification and development (MI-AID) before entering into the dyadic intervention components. This protocol is part of the Adolescent Medicine Trials Network (ATN) Scale It Up program described in this issue. METHODS: This is a comparative effectiveness trial that will be executed in 3 phases. Phase 1 will gather qualitative data related to intervention development and implementation from partnered YMSM at 4 subject recruitment venues (SRVs). Phase 2 will compare a continuum of these interventions in a pilot randomized controlled trial (RCT) at 2 SRVs. Phase 3 will compare the most successful adapted intervention package from phase 2 to CHTC as usual in a larger RCT at 4 SRVs. This phase is focused on implementation and sustainment phases of the Exploration, Preparation, Implementation, and Sustainment framework. RESULTS: Phase 1 data will be drawn from qualitative interviews with partnered YMSM (n=24) and staff from ATN sites (n=20). Baseline enrollment for phase 2 is expected to begin across 2 SRVs in June 2018 (n=36). In phase 2, survey data collection along with HIV and sexually transmitted infection (STI) testing will occur at baseline, and 1- and 3-month (postintervention) follow-ups. Phase 3 will begin enrollment across 4 SRVs in September 2019 (n=144) and follow-ups will occur at 1, 3, 6, and 9 months postintervention. CONCLUSIONS: Although MI-AID, video-based assertive communication training, and CHTC have established efficacy when administered on their own, this study will be the first to evaluate the strongest adjunctive version of these interventions to address the specific developmental needs of partnered YMSM. TRIAL REGISTRATION: ClinicalTrials.gov NCT03386110; http://clinicaltrials.gov/ct2/show/NCT03386110 (Archived by WebCite at http://www.webcitation.org/75mlO7GCx). INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/11186.