Children who begin formal schooling with stronger executive functioning (EF) capacities are better able to adapt to a more regimented learning environment and to succeed academically. Unfortunately, children growing up in low-income households are less prepared to meet the EF demands required of more formal learning environments than their higher-income peers and are therefore at a disadvantage in terms of later academic success. As a result, an important policy goal is to determine how best to support the development of EF among children growing up in low-income households prior to the start of first grade. This two-study dissertation investigates the intriguing possibility that early childhood math instruction might be one such method. In Study 1, I used latent growth curve modeling to explicitly test the hypothesis that math instruction is beneficial for EF development. I found that children who were exposed to math instruction in early childhood demonstrated greater gains in EF across kindergarten and the transition to first grade compared to those who were not. Further, I found that even small increases in the amount of time spent on math instruction in preschool was particularly beneficial for the EF development of those with the lowest incoming EF scores. These findings suggest that one does not need to implement large-scale interventions to move the needle in terms of EF development, but rather, that everyday classroom math practices can also play an influential role. Next, in Study 2, I used auto-regressive cross-lagged panel modeling to identify the "specific aspects" of early math learning that might be most likely to support growth in EF. I found that it is young children's conceptual understanding of number, rather than the fluency with which they can compare and manipulate quantities, that is particularly conducive to EF development. Together, the findings from this dissertation offer some of the first evidence to suggest that providing opportunities for math learning in early childhood -- particularly those that foster young children's conceptual understanding of number and cardinality -- may be an accessible and cost-effective method for helping children who face economic-disadvantage meet the EF demands of more formal schooling. [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.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]