This study examined the hypothesized illness self-schema construct in persons with rheumatoid arthritis (RA). Biases in self-description, information processing, and schema-consistent illness behavior were examined in depressed and nondepressed persons with RA and compared with those of depressed and nondepressed controls. Major findings revealed that RA-depressed subjects exhibited pervasively negative self-description and biased processing of negative illness-related information. RA-nondepressed subjects demonstrated a bias for positive self-description and enhanced processing of positive illness-related information. Using regression analysis, the illness self-schema construct predicted unique variance in self-reported functional disability. Findings are reviewed in the context of previous research on self-schemas, chronic pain, and cognitive variables in chronic illness. Potential clinical implications and directions for future research are discussed. The illness self-schema construct has significant heuristic value which could guide further research on the psychosocial adjustment of individuals with chronic illnesses.