Objective: The aim of this study is to determine the extent to which men’s later-life cognitive trajectories vary by veteran status. Method: We use Health and Retirement Study (HRS) data to estimate growth curve models examining men’s later-life cognitive trajectories by veteran status, war service status, and period of service. Analyses control for early-life characteristics that influence selection into military service and later-life cognition, and mid- to late-life characteristics that potentially mediate the relationship between military service and later-life cognition. Results: Veterans have higher cognition scores relative to nonveterans around retirement age, but their cognition scores decline more rapidly with increasing age, such that cognition scores are similar in both groups among the oldest old. Veterans who served during the Korean War have lower cognition scores around retirement age, but less steep age-related declines, than veterans who served during World War II. Discussion: Findings are discussed in relation to the extant literature, future research, potential service needs, and study limitations.