The present study utilized a sample of 198 individuals with Fibromyalgia Syndrome (FMS) to examine the association between treatment process variables (beliefs, coping strategies) and treatment outcomes (pain severity, activity level, emotional distress and life interference) related to a 4-week multidisciplinary fibromyalgia treatment program. Multiple regression analyses were utilized to evaluate these relationships pretreatment to posttreatment as well as from pretreatment to 3- and 6-month follow-ups. The results indicated that outcomes were most closely related to: (1) an increased sense of control over pain, (2) a belief that one is not necessarily disabled by FM, (3) a belief that pain is not necessarily a sign of damage, (4) decreased guarding, (5) increased use of exercise, (6) seeking support from others, (7) activity pacing and (8) use of coping self-statements. These findings are consistent with a cognitive-behavioural model of fibromyalgia, and suggest targets for therapeutic change.