The purpose of this sequential mixed-methods research was to discover the impact school culture, internal factors, and the state of flow has upon motivating a teacher to develop teaching expertise. This research was designed to find answers concerning why and how individual teachers can nurture their existing internal factors to increase their motivation to seek expertise development and to explore how school culture, internal factors, and state of flow may encourage or limit the development of expertise in order to add to the discussion of educational reform efforts. The major findings of this study included: (1) Teacher-student kinship, an almost family-like relationship, is the driving motivational force behind a teacher's development towards expertise; (2) Expert teachers can seamlessly merge their strong pedagogical, content, and interpersonal knowledge into a single expert lens through which they view all interactions and activities to positively impact student achievement; (3) Expert teachers constantly and consistently seek deep-impacting professional learning experience; and (4) Expert teachers can function at high capacity regardless of school culture, but prefer optimal school culture. These major findings hold implications for theory, practice, and future research particularly in the realm of teacher quality and the change of mindset towards the profession and the standards of education. [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.]