In a volatile, uncertain, and heterogeneous world, community philanthropic organizations play critical roles in community building. Nevertheless, few studies have examined the strategies of community philanthropic organizations in community building and the tensions they encounter in fluid communities. This study investigated four community foundations in highly mobile and diverse suburban communities and found that the strategies of community building involved highlighting the distinctiveness of locality, protecting the integrity of localities against the control of the metropolis, ensuring geographic representation of foundation leadership, and building an inclusive community identity that acknowledges diversity. Nevertheless, with the concern of alienating donors of dispersed interests, community‐building efforts have only created what Zygmunt Bauman calls the “cloakroom community,” a substitute for genuine communities, where people come together for a time, but their individual concerns are not blended into group interests, and collective actions to address community issues do not occur. This deters community foundations from effectively engaging local people and creating long‐lasting social solidarity.