Teacher perceptions of their principal are related to how they view their profession and their own self-efficacy. A mixed-methods, convergent parallel design including three multiple linear regression procedures and qualitative analyses, was used to study these factors. Participants included 125 teachers from the four regions of the United States. Regression analyses included the variables of teachers' years of education experience, number of years working with current principal (five years or fewer, six years or more), and four areas of principal support to predict three subscales of teacher self-efficacy. Qualitative data from four open-ended items addressed teachers' perceptions of principal support. A stepwise multiple linear regression indicated that instrumental support, years working with current principal, emotional support, and number of years teaching, predicted self-efficacy for instructional strategy, explaining 17.2% of the variance. Years working with their current principal and instrumental support explained 12.1% of the variance in self-efficacy for classroom management. Years working with current principal and instrumental support predicted self-efficacy for student engagement, explaining 13.1% of the variance. Classroom management and student engagement were positively related to the length of time a teacher worked with a particular principal. Teacher perspectives of these constructs revealed that teacher self-efficacy is significantly influenced by the assistance teachers receive from their principals in terms of resources, constructive feedback, and emotional support. [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.]