According to a fear-avoidance model of chronic pain, disability is largely determined by the erroneous belief that an increase in activity level is potentially harmful. Further, recent literature suggests that excessive fears regarding physical activities contribute to significant disability. However, the relation of changes in these fears to functional work capabilities has gone largely uninvestigated. The present study examined how changes in physical capability for work were related to changes in pain severity and fear-avoidance beliefs for general physical and work-specific activities, as well as investigating whether an interdisciplinary treatment program for chronic pain was associated with changes in these specific fears in 65 individuals with chronic pain. Results revealed that significant decreases in fear and pain levels occurred from pre- to post-treatment, in addition to increases in physical capability for work. Further, changes in work-specific fears were more important than changes in pain severity and fear of physical activity in predicting improved physical capability for work. These results expand previous research, which has found a relation between self-reported disability and fear-avoidance beliefs, by demonstrating the relation with fear of work to actual work-related behaviors.