Parental encouragement of illness behavior is hypothesized to correlate with psychosocial dysfunction in adolescents with chronic illness. To explore this hypothesis, adolescents aged 11 to 17 years with chronic fatigue syndrome (CFS) (n = 10), juvenile rheumatoid arthritis (JRA) (n = 16), and healthy adolescents (n = 14) were recruited for the study. Measures included the Achenbach parent and youth self report forms, the Family Adaptability and Cohesion Evaluation Scale-II (FACES II), the Children's Depression Rating Scale, and number of days absent from school. The Illness Behavior Encouragement Scale (IBES) generated measures of parental reinforcement of illness behavior. As predicted, the teens with CFS scored statistically higher on measures of depression, total competence, and number of days of school missed in the previous 6 months (mean = 40). Children with JRA scored significantly lower than the CFS group on the measure of parental reinforcement of illness behavior. The healthy group produced intermediate scores. Results and implications for future clinical and research activity are discussed.