Ethnic groups exist almost everywhere. Generally, each group is related to uniformly, although it may comprise several subgroups. An example is Israel’s Palestinian-Israeli population, which consists of three ethnic–religious subgroups: Muslims, Christians and Druze. They coexist in nearly all domains of life, but maintain separate schools and family law courts. Most of the professional literature on Palestinian-Israelis, especially in Israel, ignores their differences. This qualitative study, using semi-structured interviews conducted in 2018, highlights this lacuna in the context of the demand for multicultural social work. Participants were forty-two male and female social workers—roughly one-third each Muslims, Christians and Druze—in welfare bureaus in ethnically–religiously mixed Palestinian-Israeli localities. The findings reveal that the ethnic–religious composition of the social workers in a locality does not reflect the ethnic–religious balance of the population. Despite the interviewees’ lack of formal ethnic–religious-sensitive knowledge, they displayed informal knowledge. Nevertheless, the different needs of the three ethnic–religious groups met with undifferentiated responses. The welfare bureaus prefer a uniform policy rather than recognising differences, impeding the advancement of inter-ethnic cultural competence. This article contributes to world knowledge regarding cultural competence and highlights the need for culturally competent skills that are sensitive also to ethnic–religious subgroups.