Purpose: This study examines the structural relationships between social activities and trajectories of late-life depression. Design and Methods: Latent class analysis was used with a nationally representative sample of older adults (N = 5,294) from the Longitudinal Study on Aging II to classify patterns of social activities. A latent growth curve model captured longitudinal changes in depression and tested the impact of social activities while controlling for residential relocation, health status, insurance, and sociodemographics. Results: We found 3 different patterns of participation across 8 social activities. Specific activities of volunteering and exercise, self-perception of social activity level as "enough," and a higher participation level pattern were associated with lower initial status and longitudinal changes in depression. Implications: Assessing involvement in multiple social activities is important when using social activities to prevent and treat depression. Future work with improved measures can further clarify how specific activities may reduce risk for depression.