Effective schooling requires teachers to have professional discretion; yet in the twentieth century, bureaucratization enhanced administrative control of teaching. Teacher unionization offered one response to bureaucratization, intended in part to protect teacher professional discretion. More recently, the charter school movement offered a second means to protect teacher professionalism, though some scholars argue that charters fail to empower teachers since few charter teachers have union representation. We describe the conceptual links between unionization, charter schooling, and teacher professionalism. We then use the nationally-representative 2011-2012 School and Staffing Survey data to empirically examine the extent to which unionization and charter schooling influences teacher professionalism, measured as teachers' perceptions of control over school policies and aspects of teaching and learning. OLS regressions indicate that unionized teachers report lower levels of control, while charter teachers report somewhat greater levels of control over school policies and curricula than other public school teachers.