This study tested the relative predictive power of self-efficacy expectations of physical capabilities (functional self-efficacy [FSE]), expectations of pain, and expectations of reinjury on physical function in chronic back patients. Before behavioral assessment of function, 85 patients rated their abilities to perform essential job tasks (FSE) and the likelihood that their performances would be accompanied by pain and reinjury. Partial correlations revealed that FSE was significantly related to function when reinjury and pain were partialed out. Neither reinjury nor pain expectancies correlated significantly with function when FSE was partialed out. Further support for an FSE approach came from regression analyses that found pain intensity, gender, and FSE--not expected pain or reinjury--related consistently with physical performance. Thus, performance-specific cognitions may have greater explanatory power over disability than pain-specific ones.