AbstractPredictors for treatment outcome, i.e. changes in subjective functional capacity (FCI) and work status 12 months after treatment, were analyzed with chronic low back pain (CLBP) patients (n = 175) who attended a 4-week multimodal back treatment program with intensive physical training. Locus of control beliefs, health optimism and symptoms of depression were used as predictors.The results showed that those with more optimistic views on their health and weak belief in control by powerful others had gained from the treatment more even after controlling for the initial scores of the FCI. Those Ss who were at work 12 months after treatment had before treatment more optimistic views on their future health and weaker belief in external control. They also had a significantly greater improvement in the FCI when compared with those on sick-leave or pension at the 12-month follow-up regardless of the initial value of the FCI. Symptoms of depression were not significant predictors for treatment outcome.The results indicate that cognitive factors play an important role in the outcome of rehabilitation of patients with CLBP regardless of the initial disability caused by back pain.