Intense fear of social scrutiny represents a core component of social phobia, and extinction of this fear represents the goal of exposure therapy during CBT (Cohn and Hope). Finding treatments that facilitate extinction is of paramount importance. In animals, extinction involves an active learning process that is blocked by glutamatergic NMDA antagonists and facilitated by NMDA agonists. Specifically, administration of D-cycloserine (DCS), a partial agonist at the glycine modulatory site on the NMDA receptor, produces a dose-dependent facilitation of extinction in the rat. As such, DCS might facilitate extinction during exposure-based CBT. Indeed, Ressler (Ressler et al 2004) recently reported preliminary data from a clinical trial supporting this hypothesis.