Quality of life (QoL) in the face of declining health, mobility, and social losses is a central issue for older adults. Our study examined changes in QoL over time for older adults residing in independent senior housing within continuing care retirement communities (CCRCs) and estimated how residents' social engagement during their first year influenced QoL over the next 4 years. Data were drawn from a 5-year panel study of 267 older adults who moved into senior housing within four CCRCs. Although initial QoL varied between individuals, QoL declined for the group over time. One component of early social engagement-participating in a greater number of formal social activities organized by the CCRC-significantly slowed the rate of decline in QoL. Findings suggest that senior housing residents may benefit from early participation in organized social and leisure activities soon after move-in to forestall declines in QoL over the long term.