Psychological treatments for chronic pain, particularly those based upon cognitive behavioural principles, have generally been shown to be efficacious. Recently, a treatment has been developed based upon the fear-avoidance model of chronic musculoskeletal pain, which suggests chronic pain can be relieved by exposing the individual to movements and tasks that have been avoided due to fear of (re)injury. This graded in vivo exposure treatment has been found to be beneficial in case studies. The present investigation utilized a randomized controlled trial method to assess the effectiveness of graded in vivo exposure relative to other conditions. Forty-four chronic low back pain patients were randomly assigned to graded in vivo exposure, graded activity, or a wait-list condition. While only trend differences were observed for pain-related disability, patients in the graded in vivo exposure condition demonstrated (a) significantly greater improvements on measures of fear of pain/movement, fear avoidance beliefs, pain-related anxiety, and pain self-efficacy when compared to those in the graded activity condition, and (b) significantly greater improvements on measures of fear-avoidance beliefs, fear of pain/movement, pain-related anxiety, pain catastrophising, pain experience, and anxiety and depression when compared to those in the wait-list control condition. Additionally, patients in the graded in vivo exposure condition maintained improvements in these areas at one month follow-up. Implications of these findings for the treatment of individuals with chronic low back and other pain conditions are discussed.