Although several eating disorder prevention programs reduce eating disorder risk factors and symptoms for female high school and college students, few efficacious prevention programs exist for female middle school students, despite the fact that body image and eating disturbances often emerge then. Two pilot trials evaluated a new dissonance-based eating disorder prevention program for middle school girls with body image concerns. Female middle school students with body dissatisfaction from two sites [Study 1: N = 81, M age = 12.1, standard deviation (SD) = 0.9; Study 2: N = 52, M age = 12.5, SD = 0.8] were randomized to a dissonance intervention (MS Body Project) or educational brochure control; Study 2 included a 3-month follow-up. Intervention participants showed significant post-test reductions in only one of the six variables with both Studies 1 and 2 (i.e., pressure to be thin and negative affect, respectively), though post-test effect sizes suggested medium reductions in eating disorder risk factors and symptoms (Study 1: M d = .40; Study 2: M d = .65); reductions at 3-month follow-up in Study 2 were not evident (M d = .19). Results suggest that this new middle school version of the Body Project is producing medium magnitude reductions in eating disorder risk factors at post-test but that effects are showing limited persistence. Continued refinement and evaluation of this intervention appears warranted to develop more effective prevention programs for this age group.