H. Szechtman and E. Woody proposed that obsessive-compulsive disorder (OCD) is caused by a malfunctioning brain security motivation system. In the current article, the authors' review of the model suggests that it is limited in the following ways: (a) It is built on a selective review of the empirical literature, (b) it offers no explanation for many important OCD phenomena, (c) it fails to distinguish OCD from generalized anxiety disorder, (d) some of the model's predictions are ambiguous or unfalsifiable, and (e) other predictions are refuted by previously published research. Models proposing that OCD is caused by a single dysfunctional mechanism, such as the security motivation model, have difficulty explaining the complexity and heterogeneity of OCD.