In the treatment of anxious youth, children's symptom presentations cannot always be readily distinguished as indicative of obsessive–compulsive disorder (OCD) or generalized anxiety disorder (GAD). Following a definition and brief description of the phenomenology, epidemiology, and treatment of OCD and GAD in youth, consideration is given to factors that contribute to the proximity of the two disorders. In an effort to better understand the distinctive and overlapping features of these neighboring disorders, we review (a) obsessions and worry, with reference to process, form, content, and metacognitive beliefs, and (b) the literature on pathological worry and covert compulsions. Studies from the adult literature are considered throughout, and the absence of related work with samples of youth, within a developmental framework, is highlighted. Suggestions for future research are offered.