The current diagnostic nomenclature for eating disorders has shortcomings. Empirical attempts to identify a new nomenclature have found numerous latent structures, but validation of this work has been largely cross-sectional, and nothing is known yet about the relationship of derived latent classes to mortality. This study examined latent diagnostic structure in 1,885 participants seeking outpatient eating disorder treatment over an 18-year period. Eating disorder symptoms were used as indicators, and the main validator was mortality as assessed using computerized linkage to the National Death Index. Six latent classes were derived; three of the six had significantly elevated standardized mortality ratios. It appeared that the latent class structure yielded better delineation of mortality risk than the existing classifications in the Diagnostic and Statistical Manual of Mental Disorders. These results provide support for an alternative, empirically derived diagnostic structure. PsycINFO Database Record (c) 2012 APA, all rights reserved.