Although principals in Swedish preschools treasure cultural diversity and multilingualism, diversity also involves challenges to preschool staff. They may find themselves in a position where there is no way of cooperating with parents, as prescribed in the preschool curriculum (Swedish National Agency for Education, 2018), without counteracting preschools’ fundamental values. These values concern promoting democracy, human rights, gender equality and diversity – fundamental social sustainability goals. In this study, 14 preschool principals were interviewed in focus groups. The results of the study are explored through ‘dilemmatic spaces’ (Honig, 1996), a conceptual framework useful for analysing teachers’ everyday practice. Dilemmatic spaces suggest that dilemmas are ever-present in a particular setting, such as preschools, and that this shifts the responsibility for a challenging situation from the individual to a structural level. The concept has been developed by Fransson and Grannäs (2013). This article presents dilemmas that may arise when preschool staff working in multicultural preschools strive to uphold fundamental values stipulated in the curriculum.