Tennessee school instructional leaders experienced a teacher shortage and relied upon alternatively licensed second career teachers to fill vacant teaching positions, especially in math and science. The purpose of this qualitative interpretive study was to understand alternatively licensed math and science second career teachers' perceptions of their preparedness for classroom teaching and of the support provided by instructional leaders. This study included 17 alternatively licensed second career math and science teachers who participated in a questionnaire, two of which also participated in a diary study to determine their perceptions of preparedness for their classroom teacher roles and of their perceptions of the support they received from their instructional leaders. I found alternatively licensed second career math and science teachers in Tennessee cited a lack of preparation for daily tasks (e.g., lesson planning, classroom management, handling student behavior) and feelings of overwhelm as contribution to their lack of confidence in the preparedness for classroom teaching. Second career teachers, though effective, were leaving the profession after fewer years of service as compared to their first career teacher counterparts. In this study, I investigated the aspects of preparedness and the support received from their instructional leaders, and whether either contributed to their longevity as teachers. [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.]