Despite decades of research, understanding of the employment trajectories of individuals with serious mental illnesses remains elusive. We conducted a 5-year prospective, longitudinal study using a geographically broad sample of individuals who met established criteria for sustained competitive employment (N = 529). We collected data on an annual basis with a specifically designed survey instrument. Despite stable employment at study entry, more than half of the participants experienced work interruptions during the 5-year follow-up period. Predictors of sustained employment included the absence of a trauma diagnosis, Social Security disability income, psychiatric hospitalizations, and difficulties with daily functioning. The presence of a higher quality of life, workplace supports, and a flexible job were also predictive. Results dispel the myth that people with serious mental illnesses cannot be employed for prolonged periods. Interruptions in work trajectories, however, suggest that longer-term supports may increase individuals' capacity to maintain stable employment.