Inconsistencies exist regarding the relation between physical activity (PA) and internalizing symptomology in early adolescence, and there is need for investigation of potential moderators that may account for these discrepancies. The current study utilized a Self-Determination Theory Framework to investigate the main effects of five key motivations to exercise and their moderating effects between PA and internalizing problems in an underserved sample of adolescents (n = 167; mean age = 12.19 years; 73% African American). Analyses showed that intrinsic motivations were negatively related to internalizing problems and extrinsic motivations were positively related. PA was only protective against internalizing problems when intrinsic motivations were high and had iatrogenic effects when these were low. Exploratory analyses further delineated the unique effects of motivational orientations. Clinical implications and future research directions are discussed.