The purpose of this phenomenological case study was to explore the lived experiences of National Board Certified expert teachers and how their professional capital was developed. The study sought connections between expert teachers' experiences the creation of teacher leaders as these relate to leadership, culture, professional learning, and the development of professional capital. Their narratives add details as to why some expert teachers become leaders and why others avoid leadership. Major findings of this study included: 1) Expert teachers seek deep-impacting professional learning experiences and have relationships with encouraging mentors and colleagues; 2) Positive, collaborative school cultures provide the foundation for expert teachers to thrive; 3) Expert teachers are aware of their own professional capital and willingly engage in building others professional capital, if culture permits; and 4) Expert teachers engage as teacher leaders if the culture is positive, collaborative, and student-focused. [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.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]