This study tests the association between union status and job satisfaction using 8,000+ U.S. faculty at four-year public institutions surveyed in the 2004 National Study of Postsecondary Faculty. The results from hierarchical linear models that included individual and institutional variables found that nonunion faculty reported significantly higher levels of satisfaction with their jobs' instructional and employment components. These results depended on whether faculty were nonunionized by choice, unavailability, or ineligibility. The most satisfied faculty are those at institutions that offer unionization but who have chosen not to join the union. The discussion focuses on possible causes linking unionization and satisfaction. (Contains 3 tables.)