This article addresses the question of whether body dysmorphic disorder and eating disorders, both characterized by disturbed body image, consist of obsessional or delusional thinking. Clinical descriptions and empirical evidence suggest that the answer is ''both.'' Ln addition, it is likely that the delusional and nondelusional variants of these disorders constitute a single disorder that encompasses a spectrum of insight, with the entire spectrum characterized by obsessional thinking. This more dimensional view was to some extent adopted by DSM-IV for body dysmorphic disorder (and obsessive-compulsive disorder) after considerable debate. These issues, including the relationship of obsessional and delusional thinking more generally, have classification and clinical implications for many psychiatric disorders and touch on issues of broad relevance to the field.