--- - |2+ Objective Untreated compulsive sexual behaviour (CSB) poses a risk to efficacious substance use disorder (SUD) treatment. Yet the ways in which CSB manifests in women with SUDs remains poorly understood. Shame and trauma exposure are well‐documented correlates for women's CSB. Prior theory suggested women with shame and trauma‐related symptoms may engage in CSB in an effort to escape aversive internal experiences. Thus, the present study examined experiential avoidance as a mediator of the relationship between defectiveness/shame beliefs, post‐traumatic stress disorder symptoms, and CSB in a sample of women with SUDs. Method Cross‐sectional, self‐report data were collected from 446 women (M age = 37.40) in residential treatment for SUDs. Results Experiential avoidance partially mediated the relationship between both post‐traumatic stress disorder symptoms and defectiveness/shame beliefs and CSB. Conclusions These results extend theoretical conceptualizations of women's CSB to a treatment population. CSB intervention efforts may benefit from targeting women's avoidance of painful experiences. - Clinical Psychology & Psychotherapy, Volume 25, Issue 5, Page 692-700, September/October 2018.