Obsessive-compulsive disorder (OCD) is a highly debilitating disorder. Fortunately there are treatments that help the majority of OCD sufferers. The behavioral treatment with the most empirical support for its efficacy is exposure and response prevention (EX/RP). Over the years in our supervision meetings and in our clinical practice we have noted a number of relatively common therapist pitfalls that decrease the effectiveness of EX/RP. These pitfalls include not encouraging patients to approach the most distressing situations, doing imaginal exposure when in vivo is called for (and vice versa), encouraging distraction during exposure, providing reassurance, failing to address the core fear, ineffective handling of mental compulsions, and difficulty working with close others in the patient's life. In the current article we describe these common pitfalls and how to avoid them.