Very little research is available to identify how attire in the athletic training field impacts perceptions of professional knowledge and competence. The purpose of this study was to identify the effect of attire on high school athletic directors’ perceptions of an athletic trainer’s professional knowledge and competence. The researcher emailed a questionnaire to ninety-four high school athletic directors from the state of California. The questionnaire measured the effect of attire on the perceptions of skills, knowledge, approachability, experience, education level, overall competence, and representation of an athletic trainer and focused on the difference between khaki attire, professional attire, and workout attire in relationship to perceived knowledge and competence. The respondents rated khaki attire highest followed by professional attire and workout attire when evaluating skills, approachability, overall competence, experience, and knowledge. Representation and education level rated khaki attire as the highest, followed by professional attire, and workout attire rated the lowest. These results indicate khaki attire as the most appropriate attire for high school athletic trainers to wear to achieve the highest perceptions of competence and knowledge from high school athletic directors