Unlike traditional interventions, Internet interventions allow for objective tracking and examination of the usage of program components. Student Bodies (SB), an online eating disorder (ED) prevention program, significantly reduced ED attitudes/behaviors in college-aged women with high body image concerns, and reduced the development of EDs in some higher risk subgroups. The authors investigated how adherence measures were associated with ED attitudes and behaviors after treatment. Female SB participants (n = 209) completed the Eating Disorders Examination-Questionnaire (EDE-Q; C. G. Fairburn & S. J. Beglin, 1994) at baseline, posttreatment, and 1-year follow-up. Total weeks participation and frequency of utilizing the online Web pages/journals predicted pre- to posttreatment changes in EDE-Q Restraint but not in other ED symptoms. In participants with some compensatory behaviors, discussion board and booster session use were associated with increased weight/shape concerns during follow-up. In overweight participants, higher online Web page/journal use was related to decreased EDE-Q Eating Concern scores during follow-up. This is the first study to investigate the relationship between adherence to specific program components and outcome in a successful Internet-based intervention. Results can be used to inform future development and tailoring of prevention interventions to maximize effectiveness and facilitate dissemination. (Contains 4 tables and 2 footnotes.)