Indiana University-Purdue University Indianapolis (IUPUI) / It is well documented that a variety of sports coaches lack nutrition knowledge. However, few studies explore their knowledge of appropriate weight loss methods, macronutrient intake, or disordered eating. Unfortunately, both college and high school coaches disseminate inaccurate nutrition and weight loss counsel to their respective athletes who are just as unknowledgeable. Further, there is little research, which only focuses on coaches of a specific sport (e.g. tennis). Thus, the primary purpose of this study was to assess high school tennis coaches' knowledge of macronutrients and disordered eating (e.g. symptoms and prevention). Other purposes included identifying confidence in knowledge and any differences between the participating coaches' knowledge and demographic variables. To address these purposes, the 27-question Nutrition and Eating Disorders in Tennis ("NET") Survey was created (and validated). The study design involved a one-time, voluntary assessment of the Indiana coaches' demographic variables, knowledge, sources of knowledge, and level of confidence (e.g. Not At All or Very Confident). Overall, the results revealed that the coaches lacked knowledge. The average score was 70.6%, which was below the criterion for adequate knowledge. Furthermore, the coaches lacked adequate knowledge in three of the five knowledge domains: Treatment and Prevention of Disordered Eating (63.6% ± 22.9%), Disordered Eating Signs and Symptoms (60.0% ± 21.7%), and Macronutrients (57.0% ± 22.4%). The latter was further substantiated through the responses to scenario questions (Part 3). Specifically, the tennis coaches demonstrated a significant knowledge deficiency of carbohydrates, energy needs, and appropriate scope of practice. There was no significant difference between coaches' education level, gender, or type and knowledge. However, there was in experience; the more years coached, the lower the scores. Moreover, there was a trend of overconfidence in the most missed questions. This dissertation's data can provide basis for coaches' educational programs.