Deliberate practice serves as a potential framework to understand what activities, attributes, and characteristics make an individual an expert in their chosen field or profession. Historically, deliberate practice activities included those that were highly structured with purposeful goals, frequent repetition, and active feedback with immediate remediation. Deliberate practice has never been defined within the context of supervised dietetics education; therefore, the purpose of this research was to develop a valid and reliable instrument to define deliberate practice in supervised dietetics practice, based on the opinions of practitioners and educators in dietetics and allied health professions. Segment one of the research consisted of semi-structured interviews with dietetic program directors, preceptors, practitioners, and non-dietetic allied health educators. A total of 100 themes emerged from an inductive content analysis coding method. Participants in the second segment sorted previously identified themes (100 items) into predetermined categories reflective of the constructs of deliberate practice. An instrument was created of the 55 items retained, from segment two, for use in segment three, which consisted of pilot testing the instrument. Face and content validity of the instrument were tested, and initial reliability estimates were >0.70 for most categories. Instrument evaluation from the pilot testing resulted in a 55-item instrument to be tested in segment four. Lastly, all items were subject to factor analysis resulting in a seven-factor solution with 32 items accounting for 59.72% of the shared variance. Deliberate practice within supervised dietetics education can be defined with the following characteristics: (1) opportunities to practice skills and hone knowledge; (2) experiential practice to develop innate talent; (3) skills focused on a high level of patient-centered nutrition care; (4) frequent and ongoing feedback; (5) reading and understanding evidence-based practice literature; (6) professional education and networking opportunities; and (7) environment where the student is free to make mistakes. The applied purpose of this research provides an initial definition of deliberate practice, which lays the foundation for further validation studies of the final constructed definition of deliberate practice in dietetics with the benefit of outlining which practice activities are appropriate in the education of a RD. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]