Research on social movements has usually addressed issues of movement emergence and mobilization, yet has paid less attention to their outcomes and consequences. Although there exists a considerable amount of work on this aspect, little systematic research has been done so far. Most existing work focuses on political and policy outcomes of movements, whereas few studies address their broader cultural and institutional effects. Furthermore, we still know little about the indirect and unintended consequences produced by movements. Early studies have dealt with the effectiveness of disruptive and violent actions and with the role of several organizational variables for movement success. More recently, scholars have begun to analyze movement outcomes in their political context by looking at the role of public opinion, allies, and state structures. A comparative perspective promises to be a fruitful avenue of research in this regard.