Understanding how to attract and maintain volunteers is crucial for the operation of victim support organizations. We propose that volunteerism can be understood in a similar way as collective action. Active (N = 99) and nominal supporters (N = 134) completed measures of identities (personal, social, and organizational), emotions (sympathy, outrage, and pride), and efficacy beliefs (self‐, group, and organizational). The results revealed a different pattern of predictors of volunteerism for the two samples. Among nominal supporters, commitment to volunteerism was predicted by personal identity (“I”), sympathy, and self‐efficacy; among the actively engaged, volunteerism was predicted by social identity (“we”), outrage, and self‐efficacy. These results suggest that engagement with volunteerism is associated with qualitatively different processes for those nominally versus actively supportive of volunteer efforts.