The purpose of this study was to investigate the attributes or characteristics that impact a secondary teacher's credibility, as viewed by the students, while dressed in three different attire styles. Additionally, the researcher explored how the perceived attire-dependent teacher credibility impacts students' self-reported classroom behavior. The researcher presented images of male and female teacher representations in various styles of fashion to see what secondary students thought. The researcher sought student information on various teacher traits or characteristics as they may impact perceived teacher credibility. The researcher also sought information regarding self-reported student behavior based on attire-dependent perceived teacher credibility. The images portrayed the male and female teacher representation figures from the neck down so facial features or expressions did not contribute to the overall student impression. The figures were consistent in body type and void of skin tone. The attire styles presented in the photographs represented three categories: (A) professional, (B) business casual, and (C) casual. The method used to obtain the data was a survey. The survey contained a ranking system that used a 5-point Likert scale. The scale ranged from 1, "significantly positive," to 5, "significantly negative." The data were processed using SPSS Statistics version 21 and were analyzed by the use of a two-stage least squares approach. In the first step of the two-stage least squares approach, the researcher examined the determinants of the perceived teacher credibility using teacher representations in three attire styles. During the second portion of the two-stage least squares approach, the researcher explored how the attire-dependent perceived teacher credibility impacts students' self-reported classroom behavior. The study was conducted at a Texas 4A public high school campus located in the Brazos Valley. [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://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]