Objective: The risks of anorexia nervosa (AN) are well established. Despite its severity, little certainty exists for practitioners, with ethical and financial limitations yielding few controlled studies establishing effective treatments. Thus, other methods of establishing treatment effectiveness are necessary. This study presents preliminary results of an open clinical trial of a day program for adolescents with AN. Method: Participants were 26 anorectic females, 12-18 years, who completed the "Transition Program." Results: Significant change emerged on measures of weight gain, and behavioral and attitudinal measures of eating pathology. Large effect sizes were evident for weight gain at 6 month follow-up. Preliminary trends suggest that treatment gains on these and other measures of eating pathology were maintained at 6 month follow-up. Discussion: Preliminary results support day program treatment for adolescents with mild-moderately severe eating disorders. Present outcomes are discussed with respect to the dearth of efficacious treatment options for adolescents.