Minority children are less likely to engage in non-school moderate to vigorous physical activity (MVPA) and physical activity (PA) in physical education classes, and are less fit relative to Caucasian children. Clearly, understanding the determinants of physical activity and fitness among children from minority at-risk populations is important. Thus, the purpose of the current study was to examine the determinants of physical activity and fitness in inner city Hispanic Americans, the largest minority population in the USA. Additionally, theory based physical activity and fitness related research on Hispanic-American children is sparse. Therefore, we evaluated the ability of the Theory of Planned Behavior (TPB) to predict Hispanic American children's self-reported moderate to vigorous physical activity (MVPA) and their cardiorespiratory fitness (CF). Children (N = 129, ages 9-12) completed questionnaires assessing the TPB constructs: intentions, attitudes, perceived behavioral control and subjective norm all in regard to MVPA. Students then completed a scale assessing MVPA and participated in the Progressive Aerobic Cardiovascular Endurance Run (PACER) test. Multiple regression analyses provided moderate support for the ability of the TPB variables to predict MVPA as we accounted for 10% of the variance in MVPA. The TPB variables and MVPA predicted 8% of the variance in CF. In respect to the specific variables within the TPB we found that intention was the major predictor of MVPA. Children with greater intentions to participate in MVPA reported more MVPA compared to children expressing weaker intentions. MVPA was unrelated to CF but we still predicted 8% of the variance in CF with both intention and perceived behavioral control accounting for 7% of the variance. Mean values were encouraging as they indicated that most participants felt in control of the physical activity (PA) behavior, had positive attitudes, moderately strong intentions, and perceived support from significant others (i.e., parents, classmates, physical education teachers, and classroom teachers) for their physical activity engagement. Keyword(s): exercise/fitness/physical activity, multiculturalism/cultural diversity, youth-at-risk