The purpose of this K01 is to provide the candidate with the training and mentorship to become an independent behavioral scientist with expertise on couple-based approaches to optimize engagement in the HIV care continuum (CC) in sub-Saharan Africa. Research on the HIV CC in sub-Saharan Africa has largely focused on structural and individual-level barriers and facilitators, resulting in a weak understanding of factors at the relationship level. A central component of this K01 award is the conduct of research on dyadic aspects of engagement in the HIV CC among couples living with HIV. The proposed research will be situated in Malawi, a resource-poor country in SSA where 11% of adults are HIV-infected and an estimated 8,000 Malawians die each year from AIDS-related illness. The majority of new HIV infections occur within marriage or cohabitating unions. Despite the success of ART programs in Malawi, large numbers of HIV+ individuals who are eligible for ART and who have initiated ART continue to drop out of the HIV CC. Furthermore, as more HIV+ individuals access ART while healthier, there are growing concerns about long-term adherence to ART. Using a dyadic, mixed-methods study design, the specific aims of the research are: 1) to describe how the relationship context influences engagement in the HIV CC within Malawian couples; 2) to identify the relationship-level barriers and facilitators that affec engagement in the HIV CC; and, 3) to develop a preliminary intervention to optimize engagement in the HIV CC for Malawian couples. For Aim 1, qualitative interviews will be conducted with 25 couples (50 individuals) with at least one partner who is either starting or already on ART. For Aim 2, the qualitative findings will be analyzed to develop a survey for 200 ART patients and their primary partner. The survey will collect information on relationship dynamics and characteristics, treatment knowledge and beliefs, contextual factors related to HIV care and treatment, and measures of engagement in the HIV CC (e.g., attendance at clinic appointments, adherence to ART).Medical record data and hair specimens will also be collected from respondents on ART to supplement self-reported measures of engagement in care. For Aim 3, 20 semi-structured interviews with community members and stakeholders, and 4 focus group discussions with couples will be conducted to inform the development of a relationship-focused intervention targeting optimal use of HIV care and treatment. Through this research plan, the candidate will gain practical training in four areas: (1) interpersonal theory to understand health behavior; (2) methodological skills to collect and analyze dyadic qualitative and quantitative data; (3) healthcare and clinical aspects of HIV/AIDS; and (4) behavioral intervention design and evaluation. An interdisciplinary team of mentors and scientific advisors will support the training and research plan through their combined expertise in couples-based research, dyadic data analysis, healthcare and medical management of HIV/AIDS, behavioral interventions for HIV/AIDS, and local knowledge of the Malawi context.