This research explored how a group of religious leaders and scholars understand and make meaning of their experience in interfaith dialogue, and the reported impact it had on their spiritual and professional practice. It considered a broad range of themes, including participants' motivation to engage across religious difference, their understanding of the enigmatic concept "Religion," the purpose of interfaith engagement in the modern world, and the significance and meaning they draw from such engagements. This research, thus, sought to expand present understanding of how dialogic engagement across difference shapes religious leaders' conception of their own faith and identity, and how this engagement informs their leadership in a plural and complex world. The study included 25 participants from various Jewish, Christian, Muslim, and Buddhist traditions, as well as two participants who self-described as dual-practitioners. This study used a qualitative case study method, and included researcher observation, in-depth interviews, demographic inventory, document analysis, and other data evaluation procedures that involved several phases of coding and cross case comparisons. The analysis revealed five key findings: 1) A personal relationship was the primary initial motivator to engage across religious difference; 2) Interfaith dialogue increased participants' clarity about their religious identity; 3) The deepest, most impactful learning across religious difference took place informally, not in structured dialogues or academic deliberations; 4) "Spiritual humility" was the reported impact interfaith dialogue has had on participants' spiritual practice; and 5) "Collaborative practice" was the reported impact interfaith dialogue has had on participants' professional practice. Analysis of the findings led the researcher to conclude that: 1) Relationships across religious difference are excellent leadership training laboratories; 2) The enigmatic construct "Religion" is an obstacle rather than a common denominator of interfaith dialogue; 3) The religious other is necessary for spiritual growth, vitality, and insight; and 4) Professional collaboration on equal terms models the best practice of interfaith dialogue. Finally, the study yielded recommendations for exploring the implications of these findings for the fields of adult learning and development, theological education, and further academic research of interfaith dialogue and/or comparative religion. [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.]