Psychosocial adjustment in 102 children with arthritis, ages 4-16, and their families was assessed by parents, who completed the Child Behavior Checklist (CBCL) and Profile of Mood States (POMS). On average, parental distress (POMS) was lower than reference norms. POMS distress was correlated with children's behavioral problems (r = .41) but not with children's social competence (r = .15). General linear models explained 25% of the variance in CBCL behavioral problem scores. Older age was associated with more behavior problems in males, but not females. Disease severity and disease activity were also associated with behavioral problems. Although 27% of the variance in CBCL social competence could be explained, no single predictor variable was especially strong. Poorer social competence was associated with older age and shorter disease duration. Teenagers, especially those with recent onset and those with mild disease activity, may be at increased risk for psychosocial maladjustment.