This case series aims to examine the preliminary efficacy, acceptability and feasibility of Family-Based Treatment to promote weight restoration in young adults with anorexia nervosa. Four young adults with sub/threshold anorexia nervosa were provided 11-20 sessions of Family-Based Treatment for young adults with pre-, post- and follow-up assessments. At post- and follow-up, 3/4 participants were in the normal weight range, 3/4 were in the non-clinical range on the Eating Disorders Examination and reported being not/mildly depressed. At post-treatment, 2/4 were in the good psychosocial functioning range and by follow-up, 3/4 were in this range. These results suggest that Family-Based Treatment for young adults with anorexia nervosa is a promising treatment.