The purpose of the current study was to investigate desired weight percentage and weight difference percentage and their association with treatment outcome in a novel family-based partial hospitalization program. Twenty-six adolescents with anorexia nervosa or subthreshold anorexia nervosa between the ages of 12 and 19 completed the Eating Disorder Examination (EDE) at intake and upon completion from a partial hospitalization program in which parents played a large role in the recovery process, consistent with family-based treatment principles. Lower desired weight percentage at baseline was associated with higher scores on the restraint subscale of the EDE at end of treatment. Higher weight difference percentage (greater desire to lose weight) at baseline was associated with higher scores on all EDE subscales and global score at end of treatment. Neither desired weight percentage nor weight difference percentage at baseline were associated with treatment dropout or percent expected body weight at end of treatment. In a family-based program, participants' desired weight may be related to eating disorder thoughts (for example, shape or weight concerns) but not to behavioral outcomes such as weight gain or treatment dropout, which may be more directly under the influence of the parents.