We suggest that the relationship between group cohesion and collective action intentions may be affected by the characteristics of the group taking the action. However, understanding this relationship is made difficult by challenges associated with defining and measuring cohesion, and how it differs from social identification. We conducted an online survey (N = 331), in which we asked participants to nominate a group of which they were a member, then answer questions about the characteristics of that group. Then, they completed measures of perceived group cohesion and social identification, read a scenario about their group being told to disband, and then completed a measure of collective action intentions. A factor analysis showed that the measures of group cohesion and social identification were conflated, but that the items could be divided into four constructs that differentiated between in-group bonds, task cohesion, self-and-group commonalities, and in-group centrality-diffusion, respectively. We found that group characteristics changed the relationships between those constructs and collective action intentions. Thus, researchers seeking to study the effect of group cohesion on action intentions should consider both the nature of the group and the measurement of cohesion in the design of their research, as both aspects will affect their findings.What is the significance of this article for the general public? This study shows that to understand how and why group members may be motivated to mobilize to take action, it is necessary to understand their group's characteristics and the extent to which those characteristics shape the extent to which group members can cohere around a task, how bonded they are to each other, and how central the group is to individual group members' identity, respectively.