Project Summary/Abstract Significant work demonstrates the influence of spouses on one another’s emotions, behaviors, and health- related outcomes. What is not understood is the role partners play in cognitive development, change, and adaptation in middle and later life. Because researchers have not identified the biobehavioral mechanisms and processes that couples employ as they navigate normative and non-normative (i.e., mild cognitive impairment, dementia) cognitive aging, development of effective behavioral interventions to maintain and bolster performance is impeded. Prospective memory (PM), or memory for future actions, is essential to health and safety (e.g., remembering to take medication or turn off a stove) and ultimately, the ability to age in place. To remain in their homes, older adults must maintain this critical memory skill. The proposed research will identify behaviors of middle-aged and older adults when they collaborate on PM tasks and determine how those behaviors and the accompanying stress response affect PM. The central hypothesis underlying this research is that significant others are inherently involved in daily memory tasks and exert substantial “partner” effects, which positively (e.g., compensation) and/or negatively (e.g., retrieval interference, increased stress) influence PM outcomes. To test the hypothesis, this research addresses four specific aims: 1) Determine the effects of individual and dyadic characteristics on collaborative PM performance in laboratory and real-world contexts, 2) Investigate social and cognitive behaviors exhibited during the collaborative process to determine the impact of dyadic behaviors on PM performance, 3) Identify the concomitant effects of partners’ stress responses and ability on collaborative PM performance, and 4) Investigate biobehavioral processes and corresponding performance within a clinical subsample of dyads for whom one partner has MCI or early-stage dementia. The research is significant because it systematically examines the commonplace (but unstudied) phenomenon of partner interactions to identify the socio-cognitive and physiological processes important to PM and how these biobehavioral pathways may differ for couples experiencing non-normative cognitive change. The work is innovative because it includes measurement of dyadic attunement and incorporates investigation of spouses who experience cognitive change at different rates and thus are faced with the need to compensate for a partner who is struggling with the cognitive tasks of daily life. The proposed research is essential to achieving our goal of developing behaviorally-based interventions to enhance critical everyday memory behaviors and promote independent living.