This study sought to empirically derive and validate clinically relevant personality-based subtypes of anorexia nervosa (AN).Women (N = 116) with full or subthreshold AN completed baseline measures of personality, clinical variables, and eating disorder (ED) symptoms, followed by two weeks of ecological momentary assessment (EMA). A latent profile analysis was conducted to identify personality subtypes, which were compared on baseline clinical variables and EMA variables.The best-fitting model supported three subtypes: underregulated, overregulated, and low psychopathology. The underregulated subtype (characterized by high Stimulus Seeking, Self-Harm, and Oppositionality) displayed greater baseline ED symptoms, as well as lower positive affect and greater negative affect, self-discrepancy, and binge eating in the natural environment. The overregulated subtype (characterized by high Compulsivity and low Stimulus Seeking) was more likely to have a lifetime obsessive-compulsive disorder diagnosis and exhibited greater perfectionism; levels of negative affect, positive affect, and self-discrepancy in this group were intermediate between the other subtypes. The low psychopathology subtype (characterized by normative personality) displayed the lowest levels of baseline ED symptoms, co-occurring disorders, and ED behaviors measured via EMA.Findings support the validity of these personality-based subtypes, suggesting the potential utility of addressing within-diagnosis heterogeneity in the treatment of AN.