Research Findings: Drawing from a Dutch sample of 113 Dutch children ([mean] age = 37 months, SD = 3.5) from 37 early care and education classrooms (19 child care centers and 18 preschools), this study examined whether the relation between classroom emotional and behavioral support and children's observed social integration and positive mood in a play situation depends on children's observed behavioral self-regulation. Multilevel analyses revealed a positive association between emotional and behavioral support and children's social integration for children low on behavioral self-regulation, but there was no such association for children high on behavioral self-regulation. Contrary to our expectations, children low on behavioral self-regulation showed more integration in the case of relatively highly supportive classrooms but not less integration in classrooms that were low in support. For children's positive mood, a positive association with emotional and behavioral support was found, and no association was found with behavioral self-regulation. Practice or Policy: This study's findings highlight the importance of emotionally and behaviorally supportive classroom experiences for young children's social and emotional skills. Moreover, results hint that experts should perhaps not see children low in behavioral self-regulation as always at risk for poorer social outcomes. (author abstract)