Three hundred and forty-nine healthy adolescents were compared with 168 adolescents with various chronic or serious diseases on standardized measures of trait anxiety, self-esteem, and health locus of control (perception of self-control over health and illness). No differences in anxiety or self-esteem were found between healthy and ill groups or between various ill groups. Patients with oncologic, renal, cardiac, and rheumatologic disorders perceived significantly less control over their health than did healthy adolescents and patients with cystic fibrosis or diabetes mellitus. Stability of prognosis was related to low anxiety, as was length of time since diagnosis. Other physician-rated variables including course of disease, visible signs of illness, severity, and number of hospitalizations did not relate to psychologic variables. The data are interpreted as casting doubt upon the supposition that chronic or serious disease inevitably leads to psychopathology in adolescents. The overall pattern presented was one of psychologic normalcy, and attitudes regarding control over health are seen as reflecting realistic perceptions on the part of patients. The importance of looking at the effects of serious disease upon day-to-day functioning, as opposed to emphasizing inferred psychologic deviance, is stressed.