Chronic illnesses such as rheumatoid arthritis (RA) have been linked to poor psychological adjustment, although individual differences in this relationship have been observed. This study examines the role of perceived competence as a mediator between RA and adjustment. Persons with RA (N= 208) were surveyed three times at 6-month intervals concerning several potential antecedents of adjustment (pain, psychosocial impairment, social support, and control beliefs), self-perceived level of competence, and level of adjustment (life satisfaction and depressive symptomatology). Within each observational period strong evidence was obtained for perceived competence as a mediator of adjustment. Longitudinally (across the year) the data were consistent with a mediational model, but strong evidence establishing mediation was not obtained. Implications of these findings, and the importance of examining the role of perceived competence in adaptation to chronic illness, are discussed.