A model of factors that lead members of an advantaged group to perform collective action intended to help a disadvantaged out-group is tested. A distinction is made between easy and demanding collective activities. Two different routes are expected to lead to collective action. First, an indirect link is proposed between a common in-group identity and collective action. This link is believed to be mediated by perceived mobilization resources. Second, the link between relative deprivation on behalf of others (RDBO) and collective action will vary according to the type of behavior considered. While, RDBO is expected to be directly associated with easy collective behavior, the link between RDBO and demanding collective activities is mediated through perceived mobilization resources. In turn, perceived resources are linked to both forms of collective behaviors. The predicted model is tested among 273 undergraduate respondents. Findings point to the relevance of all factors considered and the pivotal role of perceived mobilization resources on collective action.