Anorexia Nervosa (AN) is a serious disorder associated with significant psychiatric and medical morbidity and mortality and high treatment costs due to the use of intensive treatment. Evidence suggests that FBT for adolescent AN is an effective outpatient treatment both at the end of treatment and 4-5 year follow-up. Using FBT, about 50% of participants remit (%IBW>95 + EDE >1SD of the mean) and 90% of those fully remitted at post-treatment, remain so at 12-month follow-up. In contrast, 75% of those not fully remitted at post-treatment are still not remitted at follow-up. Because there are no known effective treatments for adults with AN, and adolescents with AN appear to be more responsive to treatment, efforts to improve outcomes in this age group are critical to prevent the development of a chronic and unremitting course. However, when response to FBT is inadequate, more intensive programmed treatment (e.g. day treatment, residential care, or psychiatric hospitalization) is often recommended. Despite the common use of such programs, available data do not suggest that these interventions are more effective than outpatient interventions in adolescents. An alternative strategy to improve outcomes for those that do not respond to FBT would be to provide additional and targeted outpatient help directly to families themselves. Data suggest that families that are not likely to be successful in FBT can be identified as early as one month into treatment. Consequently, providing an alternative therapy early in the treatment course may enhance overall outcome. To develop a new treatment - Intensive Family-Focused Treatment (IFT) to improve outcomes in those who do not show an early response to FBT we propose a 2-phase treatment development study which aims to (1) identify modifiable family factors/behaviors that interfere with accomplishing weight restoration, and (2) develop a new family treatment (IFT) targeting unhelpful behaviors and promoting helpful ones (Phase 1 - Iterative case series (n=40)), and (3) pilot IFT (for those not responding early to FBT) vs. FBT alone in a small RCT, and (4) explore familial and individual factors as predictors, moderators, and mediators of treatment (Phase 2 - Small RCT (n=50)). To achieve these aims, this study will recruit 90 adolescents with AN (DSM-IV, exclusive of amenorrhea) and their families at two sites (45 participants at The University of Chicago and 45 at Stanford University). Primary outcome will be full remission from AN (%IBW>95 + EDE >1SD of the mean). Assessment of primary outcome as well as potential predictors, moderators and mediators will occur at baseline and at the end of treatment and will include eating related psychopathology in the parent and child (Eating Disorder Examination), Yale- Brown-Cornell-Eating Disorder, height/weight, general psychopathology in parent and child, family status, and family functioning. PUBLIC HEALTH RELEVANCE: Anorexia Nervosa (AN) has the highest mortality rate compared to any other psychiatric disorder. The most promising treatment for adolescents with AN is family-based treatment (FBT). However, only 50% of patients receiving FBT fully remit at 12-moth follow-up. Consequently, providing an alternative therapy early in the treatment course for those not responding to FBT may enhance overall outcome. This study aims to develop a new treatment - Intensive Family-Focused Treatment (IFT) - to improve outcomes in those adolescents, aged 12-18 years, who do not show an early response to FBT.