Early number sense knowledge is highly predictive of later math achievement (Herbers et al., in press; Jordan, Kaplan, Ramineni, & Locuniak, 2009; Obradovic i et al., 2009). However, research suggests that variables beyond number competencies contribute to students' mathematics achievement, most notably, executive function (Blair & Razza, 2007; Bull & Espy, 2006; Geary, 2010). Executive function refers to a set of cognitive abilities, including working memory, inhibition, set-shifting, planning, updating, and problem solving for goal-directed behaviors. To understand the constellation of skills that underpin math achievement, the present study evaluated executive function at the beginning of kindergarten in relation to number sense knowledge and general mathematics achievement at the end of kindergarten. The present study included 178 full-day kindergartners from four schools within a single school district. All students were assessed on the following skills at the beginning and end of kindergarten: number sense (Number Sense Brief; Jordan, Glutting, Ramineni, & Watkins, 2010); receptive vocabulary (Bracken Basic Concept Scales-Third Edition: Receptive-Quantity subtest); executive function (Conflict EF Scales; Carlson, 2011); general mathematics achievement (Woodcock-Johnson: Mathematics subtests; Woodcock, McGrew, & Mather, 2007); and general reading achievement (Woodcock-Johnson: Reading subtests; Woodcock, et al., 2007). Multiple regression analyses predicting end of kindergarten number sense and math achievement were conducted. Executive function at the beginning of kindergarten was a significant predictor of number sense and math achievement while controlling for initial number sense knowledge, receptive vocabulary, English language status, and kindergarten start age. To examine executive function as a mediator of initial number sense and end of mathematics achievement, a nonparametric bootstrapping method was used (Preacher & Hayes, 2008). The indirect effect associated with executive function was significant, demonstrating that executive function partially mediates the relationship between beginning of kindergarten number sense and end of kindergarten mathematics. The present findings demonstrate that children's math achievement at the end of kindergarten is directly associated with their number sense at school entry, which is partially mediated by executive function abilities. Consequently, supports for EF abilities that are embedded in mathematics intervention may offer children an opportunity to develop compensatory skills to enhance mathematics learning. Future research should evaluate interventions in randomized studies targeting EF abilities, such studies can unpack whether improvements in EF abilities have direct, sustainable effects on mathematics performance and offer broader, observable benefits in multiple domains of learning. [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.]