In response to commentary by S. Taylor, D. McKay, and J. S. Abramowitz, the authors discuss the distinctive features of their theory of obsessive-compulsive disorder outlined in their original article, which explains the disorder as a dysfunction of a security-motivation system. The authors address issues of the interrelation of emotion, cognition, and behavior in the disorder; starting versus stopping as the underlying dysfunctional problem; and the origins and possible significance of symptom heterogeneity in the disorder. In addition, the authors suggest various ways their theory of obsessive- compulsive disorder may be generative for future research.