Research Findings: This study evaluated the effects of an early mathematics intervention designed to engage preschool children, their teachers, and their families in an interactive mathematics game. Previous research shows that playing this specific type of linear board game results in increased numerical skills and understanding in young children under controlled conditions. The current study explores the game’s effectiveness under more natural conditions – a classroom-based intervention with teachers and a related family engagement component. A pilot study informed a larger-scale experiment, comparing outcomes in multiple skill domains (verbal counting, counting on, number line estimation, numeral magnitude, and numeral recognition) with those of control group children who played memory matching games. The analysis sample included 256 children in classrooms that were randomly selected from volunteer teachers and randomly assigned within 10 centers to either the treatment group (mathematics games, 23 teachers) or the comparison condition (matching games, 22 teachers). The intervention resulted in positive impacts for numeral identification, but not the other domains. The number of math games played was positively associated with verbal counting. No impact of family game play was found; however, implementation challenges could have influenced this finding. Practice or Policy: Including simple, research-informed mathematics board games in the preschool classroom can support mathematical learning. Future work must include families and educators in the design of these supports. (author abstract)