Overuse injuries in youth athletes are associated with risks, including sports specialization, biological maturation, female sex, and workload measures. As no assessment tool exists to evaluate risk accumulation, we developed a novel risk factor scoring system (Sport Training Assessment of Risk [STAR]) to assess participants' risk of overuse injury and explore association with return-to-play (RTP) time periods. (1) STAR will reach an acceptable predictive threshold in the assessment of overuse injury in youth athletes. (2) Higher STAR scores will be associated with increased RTP time periods after injury. Longitudinal cohort study. Level 3. Youth athletes with an injury sustained during competitive sport completed questionnaires. Association of questionnaire variables with injury risk type was evaluated via logistic regression analyses, and unweighted and weighted versions of a total risk score were developed. RTP was defined by physician clearance per electronic medical record review. Mantel-Haenszel chi-square tests and Kendall's rank correlation coefficients were used to assess the relationship between weighted total risk score and RTP time periods. The weighted STAR model was analyzed with receiver operating characteristic (ROC) curves. The weighted STAR model trended toward an acceptable level of prediction for overuse (nonserious + serious) injury (area under the ROC curve [AUC], 0.66; 95% CI, 0.61-0.71), but was less predictive for serious overuse injury (AUC, 0.63; 95% CI, 0.55-0.71). Weighted total risk score was weakly associated with return to full play (ρ = 0.11; P < 0.01), and potentially with return to modified play (ρ = -0.08; P = 0.04). STAR may be a feasible tool for assessing overuse injury risk and RTP time periods in youth athletes but requires further development, as it did not reach an acceptable predictive threshold in this preliminary study. Clinicians can use STAR to assess overuse injury risk in youth athletes.