Whether examining the indigenous rights movements in Latin America, the Civil Rights Movement in the United States, or the 15-M Movement in Spain, one will find that social movements around the world are deeply connected to the political realities in which they originate. But what are the political, social, and economic circumstances and contexts and variables that generally lead to the development of social movements? What motivates people to join them? What methods do members of social movements employ to reach their objectives? Are there internal and external features that are necessary for their success? And what role do social movements play in democratizing and democratic states?