PROJECT SUMMARY/ABSTRACT Despite evidence that: 1) older people living with HIV (PLHIV) experience a high burden of stress that is associated with myriad poorer outcomes, 2) psychological resilience may buffer the negative effects of stress in older PLHIV, and 3) older PLHIV may possess lower levels of this protective factor than seronegative counterparts, little work has examined strategies to bolster resilience in older PLHIV. In line with the mission of NIH and PAR-21-069, this R21 proposal, guided by preliminary studies, the Stage Model for Behavioral Intervention Development, and a strong research team, will advance the science on resilience interventions by including: 1) AN IMPORTANT UNDERSTUDIED POPULATION: older PLHIV in the Deep South; 2) A THEORY-DRIVEN RESILIENCE FRAMEWORK: Guided by The Transactional Model of Stress and Coping, the Protective Factor Model of Resilience, and the Broaden-and-Build Model, we operationalize resilience as a process whereby individuals with a set of malleable resilience resources for both appraising and responding to stress are better able to avoid prolonged (or any) disruptions in functioning. We will use a resilience curriculum that is theoretically grounded in these models and has been optimized with our pilot data; 3) RIGOROUS EXAMINATION OF EFFICACY AND MECHANISMS: We will test intervention efficacy on resilience resources and momentary stress responses using real-time methods (i.e., experience sampling method [ESM]). This RCT will randomize 100 older PLHIV aged 50+ to either an intervention condition or an attention-matched control condition. Our comprehensive battery will include proximal mechanistic measures, (i.e., ESM measurement of resilience resources and stress reactivity and recovery), and health (i.e., psychological functioning and HIV outcomes) measures. Our Primary Aims focus on intervention effects on: the use of resilience resources and whether such increases drive improved affective stress reactivity and recovery (Aim 1) and distal health outcomes at three months (Aim 2). Our exploratory aim will examine moderators of treatment response. Findings will identify intervention mechanisms and inform the development of potent and scalable interventions for building resilience in older PLHIV and other diverse populations of older adults.