OBJECTIVE We present the case of an 11 year-old girl admitted to the Centre hospitalier universitaire de Sherbrooke for a first manic episode. METHODS Differential diagnoses of adjustment disorder, attention-deficit/hyperactivity disorder, oppositional defiant disorder, and conduct disorder were considered but eliminated. RESULTS No organic etiology was detected. Her condition rapidly remitted with aripiprazole 3mg. After her discharge, she suffered a relapse due to instability of her living conditions and was rehospitalized. CONCLUSIONS Mania is a difficult diagnosis in youths due to its nonspecific symptoms, rare prepubertal occurrence, and diagnostic complexity. Despite ongoing research, there is little conclusive information on the impact of psychosocial stressors on the evolution of early-onset bipolar disorder.