Peru's HIV epidemic is concentrated in MSM, where high rates of stigma and discriminaton toward them have undermined treatment outcomes. Despite high diagnostic and linkage rates, MSM have low levels of ART initiation and viral suppression related to low retention in care. For MSM with HIV, multi-dimensional stigma related to sexual orientation, substance use disorders, sex work, multiple sexual partners, etc. undermine treatment efforts through numerous clinical interactions that have the potential to reinforce stigma and delay ART initiation. This grant proposes a transformative approach to reduce HIV-related stigma through a Behavioral Design Intervention (BDI) that utilizes same-day ART (SD-ART) protocols to streamline the treatment initiation process. Unlike other stigma-reduction interventions, BDIs operate at the organizational level, rather than at the clinician or patient level. Our strategy builds upon robust evidence that rapid-start ART (RS-ART) significantly increases ART initiation, retention and viral suppression, thus improving individual and public health. To address the entrenched stigma and operational barriers that persist in treatment initiation, this research will deploy innovative methodologies and technologies. We will first develop a tailored SD-ART protocol utilizing asynchronous online focus groups and flowcharting techniques to map the current ART initiation process and design a streamlined SD-ART protocol. This protocol will use choice architecture to streamline the ART initiation process by minimizing clinical interactions that can reinforce stigma. Using nominal group techniques (NGT), a mixed methods strategy, we will assess multi-level barriers and facilitators to SD-ART from the perspectives of patients (MSM), clinicians, and administrators. From this process, scripts for framing and nudging will be created to inform refinements to the SD-ART protocol to ensure it addresses the specific needs of MSM and thereby enhancing its effecti