The present study examined the relation between teachers' cultural backgrounds, their beliefs regarding group processes, their actual support of group processes, and children's behavior in center-based childcare in the Netherlands. For this purpose, 57 teachers of native Dutch and immigrant Moroccan-Dutch, Turkish-Dutch, Surinamese-Dutch, and Antillean-Dutch backgrounds were interviewed about their teaching beliefs and observed while engaging in a constructive play activity with small groups of children. Clear cultural differences in beliefs and corresponding behavior were found. In the interviews, the Turkish-Dutch and Moroccan-Dutch teachers mentioned concepts relating to group processes more often than the Dutch and Surinamese- and Antillean-Dutch teachers did, and they showed higher support of group processes during play. Moreover, the degree to which teachers expressed beliefs in group processes was significantly correlated with support of group processes by the teacher and with levels of collaboration and cognitive engagement in children's play. Structural equation modeling was applied to test direct and indirect effects, confirming the hypothesis that comparatively elaborate beliefs of teachers on group processes result in practices supporting group processes as well as more collaboration and cognitive engagement in children's play. (author abstract)