The investigation will enroll up to 80 pediatric subjects with OCD including some who have both autistic spectrum disorder (ASD) and OCD. The subjects will participate in a double-blind, placebo-controlled 12-week trial of riluzole as a sole agent or as an augmentation to their currently inadequate therapy. Following the double-blind portion of the trial, subjects may receive three months of open-label treatment with riluzole, if it is clinically indicated. All subjects will be followed at regular intervals until one year from baseline.