Introduction: In recent years, the sports community has been faced with the challenge of determining when it is safe to return concussed athletes to play. Given that return-to-play decisions are partially dependent upon athletes' endorsement of symptoms, better understanding what factors contribute to the presence of symptoms following concussion is crucial. The purpose of the present study was to better characterize the symptoms that athletes endorse at baseline and to determine what impact various premorbid (or preinjury) characteristics have on the presence and severity of postconcussion symptoms in the acute injury period following concussion. Method: Two groups of participants with similar ages and levels of education were examined: athletes at baseline (N = 702) and postconcussion (N = 55). Athletes were administered a comprehensive battery of neuropsychological tests, consisting of neurocognitive and neurobehavioral measures, at both time periods. The main outcome measure was the Post-Concussion Symptoms Scale (PCSS). A factor analysis was conducted on the participants' baseline PCSS data to determine the factor structure of the PCSS, and separate logistic regression analyses were conducted that examined the baseline PCSS symptom clusters (derived from the factor analysis), demographic variables, and baseline neurocognitive variables as predictors of dichotomized postconcussion PCSS total scores (i.e., low versus high symptom reporting following concussion). Results: Four distinct clusters emerged from the factor analysis measuring cognitive, physical, affective, and sleep symptoms. Logistic regression results indicated that the physical and affective symptom clusters at baseline reliably predicted athletes' postconcussion symptom group, as did sex and the neurocognitive composite score. Conclusions: These findings show that certain baseline characteristics of athletes confer risk for greater symptomatology postconcussion. Knowledge of these risk factors can assist the management and treatment of sports-related concussion.