This study examines the way coping styles and locus of control contribute to the prediction of psychosocial adjustment in adolescents with a chronic illness. Psychosocial adjustment of 84 adolescents aged 13-16 years with a chronic illness was assessed with measures of social adjustment, global self-esteem and behavior problems. Linear regressions were performed with demographic factors (age and gender) and stress-processing factors (coping style and locus of control) as predictor variables. Results indicated that coping styles were related to most aspects of social adjustment. The coping styles 'seeking social support' and 'confrontation' were important predictors for positive social adjustment; the coping style 'depression' was a predictor for poor adjustment, viz, low social self-esteem and high social anxiety. Avoidance and locus of control were not strongly associated with psychosocial adjustment. Clinical implications of these findings were discussed in terms of preventive interventions for adolescents with a chronic illness.