This paper is part of a case series illustrating the application of different therapies to a case of obsessive-compulsive disorder (OCD). It describes the hypothetical application of Acceptance and Commitment Therapy (ACT). This paper covers the philosophy and basic research on language and cognition that inform ACT. It also provides an ACT-based case conceptualization of this case and examples of therapeutic procedures. The goal of this paper is to familiarize clinicians with the use of ACT for OCD. (Contains 1 figure.)