An anti-war movement (also antiwar) is a social movement, usually in opposition to a particular nation's decision to start or carry on an armed conflict, unconditional of a maybe-existing just cause. The term can also refer to pacifism, which is the opposition to all use of military force during conflicts. Many activists distinguish between anti-war movements and peace movements. Anti-war activists work through protest and other grassroots means to attempt to pressure a government (or governments) to put an end to a particular war or conflict.

A peace movement is a social movement that seeks to achieve ideals such as the ending of a particular war (or all wars), minimize inter-human violence in a particular place or type of situation, including ban guns, and often linked to the goal of achieving world peace. Means to achieve these ends include advocacy of pacifism, non-violent resistance, diplomacy, boycotts, peace camps, moral purchasing, supporting anti-war political candidates, legislation to remove the profit from government contracts to the Military–industrial complex, banning guns, creating open government and transparency tools,  direct democracy, supporting Whistleblowers who expose War-Crimes or conspiracies to create wars, demonstrations, and national political lobbying groups to create legislation. The political cooperative is an example of an organization that seeks to merge all peace movement organizations and green organizations, which may have some diverse goals, but all of whom have the common goal of peace and humane sustainability. A concern of some peace activists is the challenge of attaining peace when those that oppose it often use violence as their means of communication and empowerment.