Guided by Self-Determination Theory, this study examined the relative importance of perceived coach supports in facilitating at-risk boys’ motivation toward physical activity. Participants were 76 at-risk boys ( Mage = 11.87 years, SD = 1.22) at a summer sports camp in the southwestern USA. Data were collected using two established questionnaires and analyzed through commonality analysis. Perceived supports for autonomy, competence, and relatedness together explained 25.5% of variance in autonomous motivation, and perceived competence support was the most powerful predictor. In predicting amotivation ( R2 = .19, p < .001), perceived competence support and perceived relatedness support were significant individual predictors while perceived autonomy support emerged as a suppressor. Perceived competence support appeared to be the strongest predictor of autonomous motivation, and the three supports were all important to diminishing amotivation. The results suggest that in similar physical activity settings, coaches should provide supports for competency, connectedness, and autonomy among participants.