Juvenile Idiopathic Arthritis (JIA) is a chronic rheumatic disease associated with pain and maladjustment. This study investigated whether pain, acceptance of pain, and psychological inflexibility uniquely predicted functional disability, anxiety, general quality of life (QOL), and health-related quality of life (HQOL) among adolescents with JIA. Twenty-three adolescents with JIA and pain were recruited from a pediatric rheumatology clinic. Participants completed self-report measures pertaining to the key study variables. A series of multiple regression analyses demonstrated that higher pain uniquely predicted higher functional disability. Greater psychological inflexibility uniquely predicted higher anxiety, lower general QOL, and lower HQOL. Increases in acceptance of pain were found to be uniquely related to increases in general QOL. These data confirm prior findings that pain impacts functioning, and provide preliminary findings that psychological inflexibility and acceptance may be important targets of psychological intervention for youth with JIA and pain to improve functioning and QOL.