It is important to appreciate the enormous diversity in the presentation and prognosis of sport-related concussions (SRC) in athletes. Duration of recovery is highly variable and partly attributable to injury severity, but a comprehensive evaluation must also include age and sex. Research on the interaction of these variables among youth athletes is limited. PURPOSE: To evaluate the effect of age and sex on the presentation of SRC symptoms in student-athletes undergoing prolonged recovery. METHODS: A sample of athletes from middle school to college (n=76) were evaluated for persistent symptoms of SRC. Cognitive function was measured using the ImPACT test; behavior and attitudes were collected via the Behavior Assessment System for Children (BASC) questionnaire. Independent-samples t tests, chi-squared tests, and multivariate analyses with a Bonferroni correction measured differences between sexes and scholastic grades on cognitive, behavioral, and functional assessments. RESULTS: Subjects were 16.2 ± 2.3 years of age; 56.6% of patients were male. Men and women expressed no differences in age (p=0.780), number of previous concussions (p=0.231), or duration of current symptoms (p=0.445). Men tested higher in verbal memory (p=0.036), visual motor speed (p=0.003), and cognitive efficiency (reaction time and accuracy; p=0.007). Women reported better attitudes toward school (p=0.005) and teachers (p=0.043). College athletes sustained more previous concussions (2.6) than middle school (1.0) and high school (1.0) athletes (p=0.016), but high school athletes expressed a trend for more co-occurring diagnoses (1.4) than middle school (0.9) and college (0.6) athletes (p=0.057). The difference between high school and college was significant (p=0.029). Regarding performance, there was a difference between grade levels in the cognitive efficiency index with middle school athletes scoring significantly lower than high school and college athletes (p=0.022). CONCLUSIONS: When youth athletes experience SRC, the sex and age of the athlete is associated with important differences in attitudes, memory, and functional capacities. Proper evaluation of a concussed athlete must consider the role that age and sex play on the diagnosis of injury severity and the expectations of recovery.