Springtime 1989 brought reports of numerous collective actions from around the world. Following a decade of underground struggle, the trade union Solidarity swept almost all the parliamentary seats from Poland's bankrupt Communist Party in the first free elections since the end of World War II. In Beijing's Tiananmen Square, tanks crushed students and workers who were peacefully demanding democratic freedoms and an end to corruption in China's Communist Party. In West Germany, masked rioters injured hundreds of police in Berlin's squatter district, while rallies of resurgent right-wing political parties increasingly erupted in bloody fights with leftist hecklers. In Israel's occupied territories, the intifada entered its second year, the rock-throwing Arab youths buoyed by the declaration of Palestinian independence and the United States' agreement to talk with the Palestine Liberation Organization. Abortion foes and advocates in the United States stepped up their mass marches, clinic sit-ins, and political agitation, galvanized by the Supreme Court's restrictions on women's freedom of choice.

As these highly visible collective actions attest, social movements take a diversity of forms and seek a variety of objectives. What they share are coordinated efforts by people holding a common interest in social change who resort to nonconventional political means to reach their goals. Whenever such collective efforts fall outside the framework of institutional political systems, we define them as social movements.