The structure of lay people's concepts of childhood mental disorder was investigated in a questionnaire study and examined for convergence with the Diagnostic and Statistical Manual (DSM-IV). Eighty-four undergraduates who had no formal education in abnormal psychology rated 54 conditions--36 DSM-IV childhood disorders and 18 non-disorders--on features proposed in technical definitions of mental disorder. The lay concept of childhood mental disorder was narrower than the DSM-IV, although most conditions were perceived to warrant professional help. Three dimensions described beliefs about childhood psychopathology: social deviancy, harmful dysfunction, and harmful environment. Harmful dysfunction was related to mental disorder and help seeking judgments.