This study examined the convergent validity between a third-party rating scale of executive function (EF) and a task-performance measurement of EF; examined the effects of age, gender, and dual language experience on preschool children's EF skills (inhibition, working memory (WM), and shifting) and on early mathematical skills; and investigated the contributions of inhibition, WM, and shifting to early mathematical skills. Ninety-two children attending Head Start were assessed. Correlation analyses revealed a number of relationships between the EF rating scale and the EF task-performance measure. A multivariate analysis of variance revealed a main effect of age on all EF measures and the math assessment and a significant difference between language groups on the measures of inhibition and shifting. Finally, hierarchal regression analyses revealed that WM and inhibition made unique contributions to children's early mathematical skills, and vocabulary scores made more contribution to early mathematical skills than either inhibition or WM. These findings extend previous research by (a) highlighting the issues involved with the assessment of EF in young children; (b) further supporting findings of preschool age-related changes in EF; (c) demonstrating EF differences with a DLL population; and (d) highlighting the importance of WM, inhibition, and language to mathematical learning, demonstrating the effects in early childhood. Implications of these findings for EF assessment in young children and prekindergarten curricula are discussed. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]