In this study we described development of boys' and girls' games on the school playground at recess as they progressed across the first year of primary school in London (UK) and Minneapolis (USA) in order to document age-related trends in games during this period and to examine the predictive role of games in children's adjustment to school and more general social adjustment. Consistent with expectations, games accounted for a significant portion of children's, but especially boys', behavior during recess. American children played games more frequently, especially simple games, relative to English children. Consistent with expectation, the complexity of games increased, especially for boys, across the school year for children in both countries. We also examined the extent to which facility with games forecasted adjustment to school and social adjustment. Games predicted both, but only in the USA sample. Results are discussed in terms of games being an important developmental task for children of this age. Implications for future research and educational policy are discussed.