After distinguishing between collective and social identity, we expound on collective ethnic identities of the Islamized ethnic groups, and the notion of a superordinate Bangsamoro social identity that includes both Tausugs and Maguindanaons. We likewise examine how collective and social identities can be linked with a peacebuilding variable, namely support for the Bangsamoro Basic Law (BBL). Based on survey data from Cotabato and Jolo, our significant mediation results show that psychological orientations can mediate how one’s sociological classification impacts on peacebuilding. Fixed ethnic identities can fracture a united Moro front toward peacebuilding in Mindanao. However, the influence of collective identities on an individual’s support for the BBL is diluted by the dynamic psychological identification with the Bangsamoro. Rather than collective ethnic identity, it is this superordinate identification that more strongly shapes support for the BBL.