Introduction: Decisions regarding return to play after sports-related concussion partially revolve around athletes' self-reported symptoms. Given this emphasis on symptoms, it would be beneficial to be able to identify characteristics that could predict which athletes may be susceptible to developing an increase in postconcussion symptoms following head injury. The purpose of this study was to describe the symptoms that athletes endorse immediately following concussion and to determine what impact injury-related characteristics have on the development of postconcussion symptoms within the first week following concussion. Method: Participants included 54 collegiate athletes who sustained concussions and were referred to our concussion management program for postconcussion testing. The main outcome measures included the Post-Concussion Symptom Scale and an interview querying athletes' retrospective symptoms over time, starting immediately postinjury. Results: Descriptive statistics revealed that the most common immediate symptoms following concussion include dizziness (endorsed by 83.6% of the sample), headache (65.5%), feeling in a fog (61.8%), and visual disturbance (60.0%). Logistic regression analyses indicated that retrograde and anterograde amnesia, as well as loss of consciousness, were not significantly predictive of postconcussion symptoms within one week following concussion (p >.05). However, the total symptom score assessed immediately postinjury, in addition to endorsing immediate headache symptoms following concussion, reliably predicted a higher level of symptom reporting in the first week following concussion (p < .05). Finally, receiver-operating characteristic (ROC) curve analysis, using 80% sensitivity to predict the high postconcussion symptom group, established cutoff scores of 7.5 for the immediate total symptom score and 0.5 for immediate headache. Conclusions: These findings demonstrate the importance of evaluating symptoms immediately following concussion. Athletes who endorse more immediate postconcussion symptoms, especially headache symptoms, may be at risk for greater and more severe postconcussion symptoms within the first week following concussion. The present findings have implications for the management and treatment of sports-related concussions.