This case study investigates the potential professional outcomes of International Service Learning (ISL) on high school teacher participants. Specifically, the aim of this study is to examine the degree to which teacher participation in ISL programming leads to pedagogical enrichment and/or perspective transformation upon their post-trip return to the classroom. The study draws from the perspective of six teacher participants. In their interviews, they commented on the degree to which they found their ISL experiences to have enriched their professional practice as classroom teachers. In addition, they commented on the extent to which they found these experiences to be personally transformative. With respect to their professional practice, participants reported that their ISL experience(s) did lead them to enrich selected areas of curriculum, improve elements of their pedagogy, enjoy enhanced student-teacher relationships, and engage in more meaningful reflective teacher practice. With respect to the issue of personal transformation (which is closely related to professional transformation), by using Kiely’s (2004) model of perspective transformation, evidence emerged that participants experienced shifts and disruptions to their current modes of thought. They reported two or more of Kiely’s forms of perspective transformation. This study identifies the enrichment and/or transformative potential of ISL participation for teachers, however, it also documents that such transformation can also be challenging and complex as teachers strive to turn intention into action. The study concludes with recommendations for post-trip support of teachers to enhance the enrichment and transformative potential of ISL trips on their professional practice and their personal perspective.