The aim of this study was to examine the hypothesis that attachment insecurity is associated with poorer responses to interdisciplinary treatment for chronic pain. Patients (n = 235) admitted to a 4-week interdisciplinary rehabilitation program were recruited. At pre-treatment, participants completed a battery of questionnaires assessing adult attachment styles and dimensions, as well as pain intensity, disability, self-efficacy, pain catastrophizing, and depressive symptoms. The latter measures were completed again at post-treatment. Nearly two-thirds of participants (65.5 %) reported having an insecure attachment style. Attachment insecurity was unrelated to pre- and post-treatment reports of pain intensity and pain-related disability, but was significantly associated with most other clinical variables at both time points. Regression analyses controlling for pre-treatment functioning indicated that attachment insecurity was associated with less improvement in pain catastrophizing, pain self-efficacy, and depressive symptoms. Further research is warranted to investigate the processes by which attachment characteristics influence patients’ responses to chronic pain rehabilitation.