Many children from low-income families who have received a generally effective pre-k math intervention nevertheless enter kindergarten behind their middle-income peers in math readiness. To better understand why, research has recently begun to examine the role of self-regulation in children's early mathematical learning and development. The present study examined (1) the directionality of relations between mathematical knowledge and self-regulation skills, specifically inhibitory control and persistence, within the context of a two-year preschool math intervention; (2) whether participation in a math intervention had a direct impact on either inhibitory control or persistence; and (3) whether self-regulation moderates the impact of math interventions on children's math outcomes. Participants were 526 low-income preschoolers who were participating in an efficacy study of two early math interventions. Children were assessed on early math and self-regulation skills three times over two years of preschool. Results indicated a bidirectional relation between children's measures of delay inhibitory control and mathematical knowledge, and children's mathematical knowledge predicted conflict inhibitory control and persistence. Participation in a math intervention had a direct impact on persistence, but self-regulation skills did not moderate the impacts of participation on either math intervention. Thus, a complex set of relations exists between self-regulation and mathematical knowledge in early childhood. This suggests that the effectiveness of early math interventions might be enhanced by concomitant interventions that target self-regulation. (author abstract)