In this study, children's self-regulation was observed, along with other social and academic activities in kindergarten classrooms during whole group, small group, transition and play contexts. We examined how children's self-regulation and engagement differed among classroom grouping, play and transition contexts. Results showed that students respond to opportunities for self-regulation significantly more often in small group and play contexts. Similarly, children demonstrate the highest engagement in play and small group contexts. Given that adults and other children comprise an important part of the environment for children's self-regulation, we also examined whether there were differences in the number of interactions children have with other children and educators across academic, social and play activities, and how these interactions broke down by classroom context. Findings have practical implications for educators working in early years settings; classroom grouping, play and transition contexts set the scene for children's engagement and opportunities to self-regulate. (author abstract)