The purpose of this case study explores the impact of an immersion experience to a least developed country on the vocation of lay teacher leaders in American Jesuit High Schools. Nine lay teacher leaders engaged in a four stage process of immersion from November 2009 to August 2010. The study employed the conceptual framework of Edward Hahnenberg's, "Awakening Vocation" to develop a self-understanding of a lay teacher leader's call. The writings of Paulo Freire, Fredrick Buechner and Parker Palmer informed the study's exploration of vocation. Poetry from Mary Oliver and William Stafford functioned as a method for articulating a lay teacher leader's vocation both before and after the immersion to Dodoma Tanzania. The following themes were found to influence a lay teacher leader's vocation through an immersion experience: Reverence for solitude, a unique process of self-discovery, motivation to work in an institution with a mission of Men and Women for others, solidarity with the poor and development of adaptability skills. A checklist for institutions seeking to impact a lay teacher leader's vocation through professional development was generated as a summary of the immersion experience in this case study. [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.]