When focusing on the teacher as the key variable in the classroom, professional dispositions are the greatest factor impacting student achievement (Diez & Raths, 2007; Haberman; 2004; Marzano; 2001). The intent of this study was to answer three questions: What professional dispositions impact student success in the learning environment as measured by North Carolina End-of-Grade Assessments (NCFE) data? What observed behaviors do effective practicing teachers demonstrate that stimulate student success as measured by NCFE data? To what extent do observed behaviors correlate between teacher self-professed dispositions and observations of an administrator? A key element was whether dispositions teachers indicated they demonstrated correlated to dispositions observed in the classroom. Participants included eight secondary teachers from a public school in central North Carolina. This was a mixed methods study merging the following: quantitative data from observations and student NCFE scores; and qualitative data from written response questions, a focus group session, and phenomenological research data. Data were collected through observations from me and an assistant principal, teacher self-assessments, and the participants' self-professed dispositions. Pearson's correlation coefficient indicated a relationship existed between EDA administrator observations and student achievement. A moderate, positive correlation also existed between higher performing self-professed teacher behaviors (composite of written, focus group, and teacher self-assessment) and the EDA administrator observations. This consistency of correlations indicated that a relationship existed between the higher performing self-professed teacher behavior composite and student achievement. Effective oral communication, professionalism, and preparedness for teaching and learning emerged as key dispositions, above the mean, impacting student success. [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.]