In sociology and anthropology, an action group or task group is a group of people joined temporarily to accomplish some task or take part in some organised collective action.

As an example, imagine that in a hypothetical culture, four bridesmaids are traditionally selected to play a role in a wedding ceremony, and eligibility to be chosen as a bridesmaid is dependent on being a young, female relative of the bride. Several people may fall into this social category : they have no automatic entitlement to the role but are eligible to assume it if chosen. Most members of the category who could theoretically be bridesmaids at the wedding are not selected. There are no criteria relating to kinship, age, or other such status that necessitate this, but for simpler reasons of practicality or chance four members of the category are chosen, and it is these who form the action group.

As the members of the action group are brought together on a single occassion and then disband, they cannot be regarded as constituting a fully-fledged social group, for which they would need to interact recurrently in accordance with their social identities.