The majority of individuals with eating disorders are diagnosed with eating disorder not otherwise specified (EDNOS). This meta-analysis aimed to inform potential revisions to eating disorder classification by comparing EDNOS to bulimia nervosa (BN) and binge eating disorder (BED) on measures of eating pathology, general psychopathology, and physical health. A comprehensive literature search identified 117 eligible studies, both published and unpublished, appearing in the literature from 1987 to 2007. Random effects analyses indicated that BN exhibited significantly greater eating pathology (d = 0.39) and general psychopathology (d = 0.19) than EDNOS, but BED did not differ significantly from EDNOS in either domain. EDNOS also exhibited poorer physical health than BN (d = -0.18). Moderator analyses indicated that EDNOS groups who met all diagnostic criteria for BN or BED except binge frequency did not differ significantly from full syndrome cases with regard to eating pathology, highlighting the binge frequency criterion as a potential candidate for revision in DSM-V. Meta-analytic results suggest that EDNOS is a disorder associated with substantial psychological and physiological morbidity. While certain EDNOS subtypes could potentially be incorporated into existing DSM-IV categories, others may be best conceptualized as distinct disorders.