Given the importance attributed to math talk, this study sought to test the effects of a Math Talk Learning Environment for exposing children to math talk and whether this effort would improve children's early math skills. The intervention used guided play in small group math games focused on numeracy skills. The analytic sample comprised 95 racially and ethnically diverse children enrolled in Head Start classrooms randomly assigned to one of two treatment groups or the counterfactual. Students in one group engaged in math games while being encouraged to use math language, whereas the other group engaged in the same math games without any explicit math language encouragement. Linear mixed modeling was used to regress children's residualized math gains on condition. Results showed a significant difference in the general math skills and the specific numeracy skills gained by children who participated in the two treatment groups compared to the counterfactual. No significant differences could be detected between the treatment groups; yet, there are indicators that the intervention warrants further investigation. This research parallels prior research and contributes new findings that will inform early childhood practitioners, developmental psychologists, and others interested in applying cognitive science to the classroom. The discussion includes descriptions of the supports required and challenges to fostering young children's mathematical thinking. (author abstract)