This paper considers collective action non-participation by people sympathetic but not committed to participating in actions for social change (‘sympathisers’). We conducted a thematic analysis of open-ended written accounts of the barriers to participating in sustained collective action (N = 112), finding that people can be reluctant to engage in some types of collective action. Participants wrote about the potential for detrimental consequences resulting from association with ‘protesters’, concern that they may be undermined by ‘extreme’ fringes of a movement, ambivalence about the visible performance of group normative behaviours (specifically, protesting), and trepidation about ‘loss of self’ within a group. We discuss the findings in relation to theory on social (dis)identification, social (dis)incentives, and identity performances, arguing that inaction does not necessarily stem from apathy. Rather, people may engage in motivated inaction – that is, active avoidance of some types of actions, or from affiliations with particular groups, as a response to negative inferences about the legitimacy or efficacy of some forms of collective action. Practical strategies are suggested for groups and individuals, including the potential for people to take actions for social change independently of a formally organised movement.