Research Findings: The present study explored connections between participation in structured open-skilled (e.g., soccer, basketball) and closed-skilled sports (e.g., swimming) and executive function (EF) among preschool-aged children. The sample included 197 preschool-aged children (mean age = 4.34 years, female = 48.2%, White = 83.8%). Parents reported on sport participation and children were directly assessed on three EF skills: inhibitory control, working memory, and cognitive flexibility. Results from regression models controlling for child age, physical activity, gender, race/ethnicity, parent education, and family income indicated that overall sport participation was associated with cognitive flexibility. Further, participation in open-skilled sports was associated with cognitive flexibility, and participation in mixed-skilled (participation in both open- and closed-skilled) sports was associated with working memory. Practice or Policy: These results suggest that participation in structured sports may be beneficial for the development of preschoolers' cognitive flexibility and working memory. Future research and implications of the study findings are discussed.