Obsessive-compulsive disorder (OCD) is a leading cause of health-related disability. There are two evidence-based treatments for OCD, pharmacotherapy and cognitive-behavioral therapy consisting of exposure and response prevention (EX/RP). Although effective, outcome from both treatments is often limited by patient lack of adherence to the treatment procedures. In this article, we present the rationale for using motivational interviewing (MI) to increase EX/RP adherence. We then review two published studies that used MI in different ways to foster EX/RP participation. Finally, we describe 6 cases in which we explored whether MI could help ready OCD patients who had refused or failed prior evidence-based treatment of any kind. Together, these data illustrate the promise and obstacles of employing MI to promote treatment adherence in OCD. We conclude by discussing future directions for researchers and for clinicians when using MI in this population. (Contains 2 tables.)