Social movements are sustained, collective efforts to promote or resist change using noninstitutional methods. As a form of collective action, social movements are distinguished from individual challenges and [Page 775]resistance, in that they involve the contentious actions of a group or coalition, and from momentary demonstrations of grievances, in that movements involve ongoing, sustained mobilization. Social movements seek to promote or resist social change but typically have only limited access to institutional channels including those of the state. As a consequence of either preexisting constraints, or of strategy, social movements direct actions through avenues external to existing institutional or organizational channels. This is a key distinction between social movements and some other forms of political behavior (e.g., interest groups, political parties), although movements may employ ...