By age 16, 20% of children will suffer a concussion. Many experience persisting post-concussive symptoms (PCS), the cause(s) of which remain unclear. We mapped concussion recovery to 3 months post-injury and explored non-modifiable (e.g., age, sex, pre-injury factors, injury mechanism, acute PCS) and modifiable (post-acute child symptoms) predictors of persisting symptoms in order to identify opportunities for early intervention. We conducted a prospective, longitudinal study in the emergency department of a tertiary, pediatric hospital recruiting children within 48 h of concussion (T0), with follow-up at 2 days (T1), 2 weeks (T2), 1 month (T3), and 3 months (T4). Primary outcome was T2 clinician diagnosis. Clinical history, injury mechanism, acute symptoms, and physical and cognitive function were assessed. Parents rated child behavior and fatigue, and their mental health. We enrolled 256 participants, 72% males: 62 (24.3%) were symptomatic at T2. Recovered and symptomatic groups endorsed similar pre-injury PCS, but group differences were found at T1 across all PCS subscales, except Emotional, where symptoms were not evident until T2. By T2, there was significant PCS reduction, steepest in the "Recovered" group, which also had a lower rate of pre-injury psychiatric diagnoses, acute CT scans and less severe parent-rated PCS at T1 than the symptomatic group. They all demonstrated lower parent-rated PCS and less internalizing behaviors (all,  < 0.01). No differences were detected for child age, sex, injury factors, pre-injury parent-rated PCS, or acute physical and cognitive status. Our findings also highlight the importance of considering both pre- and post-injury mental health status in managing post-concussion.