The mental health provider–nutritionist collaboration is a primary partnership in the treatment of eating disorders, and its integrity is important for good patient care. Utilizing critical incident qualitative methodology, 22 professionals who specialize in the treatment of eating disorders (12 mental health providers, 10 registered dieticians) were interviewed about instances of problems in collaborations between these two professions, and the impact and resolution of such conflicts. Findings were used to compile a list of best practices. Results are interpreted with reference to research on professional health care teams in medical settings. Implications for interprofessional education and training are discussed.