This study investigated the relationship between children's mathematics performance and physical health using data from the Early Childhood Longitudinal Study Kindergarten Class of 2010-2011 (ECLS-K 2011). A two-level hierarchical growth curve model was used to explore the relationships between childhood mathematics performance and childhood health taking moderator effects into consideration. The study results indicate that higher body mass index relates to higher kindergarten mathematics performance, holding all else constant. The results of this study have implications for educators, parents, and health providers in understanding the relationship between mathematics performance and health indicators.