PROJECT SUMMARY Transgender women (TGW), and especially those with an ethnic and racial minority status, are in critical need of tailored and enhanced HIV testing and prevention efforts. TGW are disparately impacted by HIV but are less likely to get tested for HIV. HIV testing is a critical entry point for the uptake of HIV prevention (e.g., PrEP) and HIV care and should also be leveraged to provide a link to other critical social support services, such as mental health and substance use treatment, which, if unaddressed might interfere with the uptake of HIV prevention and care practices. The proposed project aims to address these needs by developing a blueprint for the implementation of an evidence- based intervention, the Online HIV Self-Test Giveaway (OHTG), adapted to the needs of TGW in NYC. We aim to develop a blueprint for the OHTG adapted for TGW employing the Implementation Mapping approach and informed by Implementation Science guidelines. Implementation Mapping offers an ideal framework to guide the development of this process by helping to systematically map out relevant determinants, performance objectives, and outcomes from multiple ecologic levels, including that of the adapter, the implementer, and the broader environment, that structurally support the implementation strategy. Implementation Mapping includes the following four steps, that we will implement iteratively: (1) identify program adopters and implementers and conducting an implementation needs assessment; (2) specify adoption and implementation outcomes, performance objectives, and determinants, and creating matrices of change; (3) choose theoretical methods (mechanisms of change) and selecting or designing implementation strategies; and (4) produce and test implementation protocols and materials. The fifth step, the evaluation of the implementation outcomes will follow the completion of this one-year planning activity. However, we will design this evaluation as a final step in the Implementation Mapping process. Using Implementation Mapping will allow us to operationalize adaptation as a process of thoughtful and deliberate alteration of the design and delivery of OHTG with the goal to improve fit of the campaign with the needs, circumstances, and culture of TGW, as informed by the community, and with that, strengthen its effectiveness.