Background: It is well-known that marital status has a significant impact on subjective well-being (SWB). However, research examining the long-term influence of marital status on SWB after spinal cord injury (SCI) is limited. Objective: To identify the relationship between marital status and SWB trajectories over time, using 20 years of longitudinal data. Methods: We conducted a cohort study, including 1,032 participants surveyed 5 times in 1993, 1998, 2003, 2008, and 2013. Participants were identified from outpatient records of 2 Midwestern hospitals and 1 Southeastern specialty hospital. The Life Situation Questionnaire-Revised (LSQ-R) was used to measure multiple aspects of SWB. A multilevel model was applied to analyze the 5 repeated measurements. Results: The married or cohabitating participants enjoyed the best SWB at baseline, but their home satisfaction and global satisfaction declined over time and their social isolation increased slightly. For divorced, separated, or widowed people, the negative effects of marital loss attenuated over time. For single individuals, SWB, except for environmental barriers, did not change positively over time if they remained single. Conclusions: Using longitudinal data with 5 repeated measurements, our study showed a complicated relationship between marital and relationship status with SWB and how these relationships change over time for people with chronic SCI.