Although historically conceptualized as problems of youth, recent research indicates that women of all ages experience body dissatisfaction and eating disorder (ED) pathology. Despite this, existing body image interventions predominantly target youth. The Body Project (BP) has extensive support for reducing ED risk factors in younger women and girls. The current proof-of-concept study investigated the feasibility, acceptability, and estimates of intervention effect sizes of a modified BP for adult women, the Women's Body Initiative (WBI). Conducted in the Southwestern United States, adult women (N = 13) aged 29-70 (M = 49.1) participated in 4, 1-h weekly sessions, completing measures at baseline, post-intervention, and 3-month follow-up. Participants rated the program as highly feasible and acceptable. Within-subjects effects sizes were medium to large for primary outcomes (body dissatisfaction, ED pathology) and secondary outcomes (psychosocial impairment, negative affect, quality of life, nutritious food consumption, and sleep) through 3-months. Results suggest preliminary feasibility and acceptability of WBI for adult women, and support proceeding with a larger trial to investigate intervention efficacy.