The purpose of this study was to investigate relationship among principal leadership, collective efficacy, teacher efficacy and teacher commitment to the profession. For this investigation, three mediation models were hypothesized and tested. The design of this study utilized a six page survey to in-service teachers who enrolled in a Master's program. Teachers (N = 260) responded to the survey consisted of four scales on the variables of principal leadership, collective efficacy, teacher efficacy, and teacher commitment to the profession. Quantitative analysis involved examining preliminary analyses, descriptive statistics and four hypotheses testing. Data were analyzed using Baron and Kenny's (1986) meditational testing. The first hypothesis was partially supported for most of the study variables had positive significant associations. The data partially supported the first mediation model when collective efficacy was hypothesized to be the mediator of principal leadership and teacher commitment to the profession. The third and fourth hypotheses were not supported when general teacher efficacy and personal teacher efficacy hypothesized to be the mediator of principal leadership and teacher commitment to the profession. By hypothesizing collective efficacy and teacher efficacy to teacher commitment to the profession, this study has added to a growing awareness of the important influence of principal leadership to teacher commitment to the profession. Also, the lack of association between self efficacy and principal leadership in relation to teachers' commitment to the profession was a substantial addition to teacher efficacy, principal leadership and teacher commitment literature. Additional research is needed to (a) assess causal relations between other personal and organizational factor measures, (b) describe the differences in teacher commitment among teachers who have a Master's degree, are earning a Master's degree, and those who have not earned a Master's degree. [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/en-US/products/dissertations/individuals.shtml.]