In this dissertation, I examine current practices of modern competitive Irish step dance and feis music accompaniment through case studies conducted in the United States and Japan. More than twenty years after Riverdance significantly heightened the visibility of Irish dance both in Ireland and abroad, what do contemporary transnational practices of Irish step dance and music look and sound like and how do we compare these practices cross-culturally? Through a performance-based methodology, I contextualize the ways local and transnational Irish step dance and feis music (a specialized traditional Irish dance music used to accompany modern competitive Irish step dance) aesthetics and community values interact and construct one another in the “focus locations” of studios, feiseanna and oireachtasaí (local and regional competitions), performance stages, and the body— sites of performance where the modern competitive Irish step dance tradition is presented, embodied, and circulated. By discussing these local and transnational flows in grounded and particular key locations and experiences of performance, I demonstrate how Irish dance practices and ideas related to those practices are in constant negotiation and renegotiation between the major transnational regulatory body of An Coimisiún Le Rincí Gaelacha (The Commission of Irish Dance, CLRG) and the local cultures of the individual schools and dancers under its purview. As it goes through these processes of negotiation, Irish dance both homogenizes and diversifies, circulating through the transnational cultural cohort that practices it. This study informs several areas of research, including ethnomusicology, ethnochoreology, Irish dance and music studies, studies on processes of cultural globalization, and Japanese performing arts and cultural studies. In this work, I argue for a body- and performance-oriented approach to fieldwork and research for scholars of music as well as dance, noting the crucial role of embodiment for not only achieving a deeper understanding of the performing arts traditions they study, but also unveiling values and aesthetics fundamental to the communities they work with.