Objective: To examine the associations of stressful experiences and social support with cognitive function in a sample of middle-aged adults with a family history of Alzheimer’s disease (AD). Method: Using data from the Wisconsin Registry for Alzheimer’s Prevention (WRAP; N = 623), we evaluated relationships between stressful events experienced in the past year, as well as social support, and cognitive performance in four domains: speed and flexibility, immediate memory, verbal learning and memory, and working memory. We assessed interactions between psychosocial predictors, and with APOE 4 status. Results: Greater number of stressful events was associated with poorer performance on tests of speed and flexibility. Greater social support was associated with better performance in the same domain; this relationship was diminished by the presence of the 4 allele. No associations were seen in the remaining three domains. Discussion: Psychosocial factors may influence cognition in at-risk individuals; influence varies by cognitive domain and 4 status.