The impact of high quality teaching on student achievement has been well documented; however, there remains a need to more fully understand the factors that predict effective teaching. This study utilized Fenstermacher and Richardson's (2005) model of teacher quality to investigate teacher effectiveness within a preschool special education setting. Specifically, the current study focused on the social-emotional aspects of teaching, including the teacher-student relationship. The study was conducted within two schools that utilize the Comprehensive Application of Behavior Analysis to Schooling (CABAS[R]) model. CABAS[R] is an educational system based on the science of behavior. Within this system, instruction is individualized and is comprised of learn units. Teachers receive ongoing training and evaluation and a teacher rank system based on mastery of scientific pedagogy and effective practice is in place. Fifty-one teachers and teaching assistants participated in the study, which included completion of a survey and collection of learn unit data on one randomly assigned student for ten days. Participants were asked questions related to emotional exhaustion, involvement in professional activities, teacher rank, and self-efficacy and they provided information including the student's verbal developmental level, severity of impairment, and whether the student was on the autistic spectrum. They also rated the quality of their relationship with the randomly assigned student. The outcome variable was effective teaching, measured though learn units to criteria, which was calculated from the learn units delivered by one teacher to one student. Results demonstrated that the only variable that significantly predicted teacher effectiveness was teacher rank; thereby providing support for the CABAS[R] model's ranking system and the role of pedagogical competence in learning. While the teacher-student relationship was not related to the outcome variable, other important findings regarding the relationships emerged. The results indicated that the teacher-student relationships in this sample were characterized by low levels of closeness; over half of the relationships had a level of closeness that was of concern, with the majority of these relationships with students who were considered to be on the autistic spectrum. Additionally, over a third of relationships had a level of conflict that was of concern. Conflict was positively related to emotional exhaustion, which was in turn positively related to involvement in professional activities. Implications regarding teacher quality and the significance of teacher-student relationships in a CABAS[R] setting are discussed along with directions for future research. [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.]