A large and well-characterized sample of individuals with anorexia nervosa and bulimia nervosa from the Price Foundation collaborative genetics study was used to determine the frequency of anxiety disorders and to understand how anxiety disorders are related to state of eating disorder illness and age at onset. Ninety-seven individuals with anorexia nervosa, 282 with bulimia nervosa, and 293 with anorexia nervosa and bulimia were given the Structured Clinical Interview for DSM-IV Axis I Disorders and standardized measures of anxiety, perfectionism, and obsessionality. Their ratings on these measures were compared with those of a nonclinical group of women in the community. The rates of most anxiety disorders were similar in all three subtypes of eating disorders. About two-thirds of the individuals with eating disorders had one or more lifetime anxiety disorder; the most common were obsessive-compulsive disorder (OCD) (N=277 [41%]) and social phobia (N=134 [20%]). A majority of the participants reported the onset of OCD, social phobia, specific phobia, and generalized anxiety disorder in childhood, before they developed an eating disorder. People with a history of an eating disorder who were not currently ill and never had a lifetime anxiety disorder diagnosis still tended to be anxious, perfectionistic, and harm avoidant. The presence of either an anxiety disorder or an eating disorder tended to exacerbate these symptoms. The prevalence of anxiety disorders in general and OCD in particular was much higher in people with anorexia nervosa and bulimia nervosa than in a nonclinical group of women in the community. Anxiety disorders commonly had their onset in childhood before the onset of an eating disorder, supporting the possibility they are a vulnerability factor for developing anorexia nervosa or bulimia nervosa.