OBJECTIVE Although anorexia nervosa has a high mortality rate, our understanding of the timing and predictors of mortality in eating disorders is limited. The authors investigated mortality in a long-term study of patients with eating disorders. METHOD Beginning in 1987, 246 treatment-seeking female patients with anorexia nervosa or bulimia nervosa were interviewed every 6 months for a median of 9.5 years to obtain weekly ratings of eating disorder symptoms, comorbidity, treatment participation, and psychosocial functioning. From January 2007 to December 2010 (median follow-up of 20 years), vital status was ascertained with a National Death Index search. RESULTS Sixteen deaths (6.5%) were recorded (lifetime anorexia nervosa, N=14; bulimia nervosa with no history of anorexia nervosa, N=2). The standardized mortality ratio was 4.37 (95% CI=2.4-7.3) for lifetime anorexia nervosa and 2.33 (95% CI=0.3-8.4) for bulimia nervosa with no history of anorexia nervosa. Risk of premature death among patients with lifetime anorexia nervosa peaked within the first 10 years of follow-up, resulting in a standardized mortality ratio of 7.7 (95% CI=3.7-14.2). The standardized mortality ratio varied by duration of illness and was 3.2 (95% CI=0.9-8.3) for patients with lifetime anorexia nervosa for 0 to 15 years (4/119 died), and 6.6 (95% CI=3.2-12.1) for those with lifetime anorexia nervosa for >15 to 30 years (10/67 died). Multivariate predictors of mortality included alcohol abuse, low body mass index, and poor social adjustment. CONCLUSIONS These findings highlight the need for early identification and intervention and suggest that a long duration of illness, substance abuse, low weight, and poor psychosocial functioning raise the risk for mortality in anorexia nervosa.