Previous research examining family functioning in eating disorder (ED) treatment has focused primarily on outpatient settings. However, few studies have examined this aspect in partial hospitalization programs. To address this gap, this study examined family functioning over the course of an ED partial hospitalization program (PHP) in adolescent females (M(SD) age=15.66 (1.50)). Participants (n=105) completed the Family Assessment Device and Eating Disorder Examination Questionnaire at treatment admission, 1-month post-admission, and discharge. Results from repeated measures analysis of variance indicated adolescents perceived an improvement in family functioning regarding Communication, Affective Responsiveness, and Behavioral Control through 1-year follow-up (p values < .05). Neither family functioning at admission nor change in family functioning in the first month correlated with any outcomes (weight, ED symptoms, and remission). Results support that family functioning does not contribute to ED severity, and that treatment can improve adolescent perception of family functioning. Given the importance of involving the family in ED treatment, identifying mediators of treatment outcomes is critical to improve treatment efficacy. Adolescents in a partial hospital program (PHP) for eating disorders (EDs) perceived improvements in their family communication, behavior, and ability to process appropriate emotions from admission to 1-year post-treatment, although these aspects did not significantly predict treatment outcomes. The findings provide helpful information for future research on adolescents with EDs in higher levels of care and underscore the importance of exploring mechanisms of family-based treatment in PHP.