The association between preexisting anxiety, depression, and/or neurodevelopmental disorders and symptom duration among younger children who sustain concussions is not well known. The authors conducted a prospective cohort study of 569 patients presenting to a pediatric neurology clinic with the diagnosis of concussion. The authors measured associations between symptom duration and premorbid conditions, as well as gender, age, mechanism of injury, and other factors. Premorbid conditions were common in both age groups. On univariate modeling female gender, age >12 years, and premorbid conditions were associated with longer symptom duration. On multivariable modeling, females and patients ≤12 years old with a history of headaches, migraines, or a history of psychiatric conditions took significantly longer to recover than those without such conditions. Premorbid conditions are associated with a prolonged recovery from concussion among those patients ≤12 years old.