We examined the influence of physical and psychosocial variables on math and reading achievement test scores. Between 1 and 5 months prior to taking annual standardized reading and math tests, a sample of (N = 1,211) sixth through eight graders (53.7% girls; 57.2% White) self-reported levels of physical activity, academic self-beliefs, general self-esteem, and social support and participated in objective testing to obtain measures of body composition (body mass index [BMI]) and cardiorespiratory fitness. Socioeconomic status (SES) and state-based reading and math achievement test scores were provided by the school district. Regression analyses revealed that SES, academic self-beliefs, and cardiorespiratory fitness were the consistent predictors of the students’ performance in reading and math; perceived social support from family and friends and higher levels of self-esteem were related to higher reading scores for the boys only. Our findings support schools re-examining policies that have limited students’ involvement in physical education classes.