Piano accompaniment, or collaborative piano, is an invisibilized force driving classical music. This hybrid study, combining text and multimedia, explores its history, evolution, and transformation into a recognized academic discipline through archival research, expert interviews, and digital resources. This hybrid publication delves into the origins and institutionalization of collaborative piano, tracing its development from the early 20th century to the present day. It highlights a profession often overlooked, introduces pioneering figures including Gwendolyn Koldofsky, and maps the establishment of over 100 degree-granting programs across North America. With an interactive data visualization tool, QR codes linking to compelling first-hand accounts, and extensive archival materials, it offers a vivid, multidimensional journey through the field's past and present. By contextualizing the profession through analysis of its pedagogical, gendered, and institutional dynamics, this work seeks to foster a deeper understanding of collaborative piano's past, present, and future, while advocating for its recognition and advancement. Accompaniment in America: Contextualizing Collaborative Piano is essential reading and viewing for musicians, music students, educators, scholars, and administrators, as well as anyone interested in the intersection of collaborative piano history, performance practice, and academia. It is a valuable resource for both students and professionals seeking to understand the complexities of a field still broadly misunderstood and its pivotal role in classical music.