Alexis de Tocqueville observed long ago that Americans have a strong propensity to turn to associations for remedies to their social, political, and moral problems. These associations take a variety of forms, including formal organizations, informal networks, and temporary coalitions. Without such associations, American politics would be scarcely recognizable to the contemporary observer. Associations provide leadership, frame issues, mobilize resources, and undertake innumerable tasks that shape events and influence political processes.

On issues as weighty as war and peace, activists rely heavily on participation in associations. As we discuss in Chapter 1, the peace field has evolved and institutionalized over the past century such that there are a number of long-standing peace organizations – the War Resisters League, Peace Action, and the Women's International League for Peace and Freedom, to name a few – that provide stability and leadership as antiwar movements rise and fall over time. The post-9/11 period saw important new organizations added to this set, such as UFPJ, ANSWER, and Code Pink. Still, by naming these leading organizations, we have only scratched the surface of organizations that mobilize against war. It is impossible to know exactly how many organizations had at least some involvement in the antiwar movement after 9/11. As a lower bound for this number, we counted more than two thousand unique organizations that formally associated with at least one national antiwar coalition between 2001 and 2012. Some of the most well-known political organizations in the United States belong to this set, such as the NAACP, Sierra Club, Greenpeace, Service Employees International Union, and National Organization for Women. At the same time, the field was also populated with more ephemeral groups, such as Cabbies Against Bush, An Absurd Response to an Absurd War, and Sarasota for Dean.