The anti-cult movement, abbreviated ACM and also known as the countercult movement, consists of various governmental and non-governmental organizations and individuals that seek to raise awareness of religious groups that they consider to be "cults", uncover coercive practices used to attract and retain members, and help those who have become involved with harmful cult practices.

One prominent group within the anti-cult movement, Christian counter-cult organizations, oppose new religious movements (NRMs) on theological grounds, categorizing them as cults, and distribute information to this effect through church networks and via printed literature.

The anti-cult movement is conceptualized as a collection of individuals and groups, whether formally organized or not, who oppose some "new religious movements" (or "cults"). This countermovement has reportedly recruited participants from family members of "cultists," former group members (or apostates), religious groups (including Jewish and Christian groups) and associations of health professionals. Although there is a trend towards globalization, the social and organizational bases vary significantly from country to country according to the social and political opportunity structures in each place.

As with many subjects in the social sciences, the movement is variously defined. A significant minority opinion suggests that analysis should treat the secular anti-cult movement separately from the religiously motivated (mainly Christian) groups.

The anti-cult movement might be divided into four classes:

Most if not all of the groups involved express the view that there are potentially deleterious effects associated with some new religious movements.

Commentators differentiate two main types of opposition to "cults":

Jeffrey K. Hadden sees four distinct classes of opposition to "cults":