Within the field of contemporary Western art history, the careers and influence of professional art critics have attracted serious scholarly attention. The work of critics whose activities encompass an international range of artists and exhibitions, however, has rarely been examined. This dissertation provides for the first time an overview of one such person in the career of Italian art critic, historian and curator Germano Celant (1940- ), now recognized as one of the most influential interpreters of the late twentieth-century avant-garde and someone whose work aided in transforming the narrative of contemporary art history. This study provides a detailed discussion of Celant's biography, the range of his contributions to the contemporary art world, and a historiography of his writings on "Arte Povera", a term Celant coined to characterize the most influential group of contemporary Italian avant-garde artists. Among Celant's initial goals in identifying this group of Italian artists was to distinguish the unique artistic research occurring in Italy from the work of American Minimalist artists who were seen by many U.S. and European critics as leaders of the avant-garde in the 1960s. In his writings and curation of exhibitions, Celant not only foregrounded the achievements of Italian and European contemporary artists, but also sought to illustrate congruencies among artists working on both sides of the Atlantic. This dissertation analyzes Celant's efforts over the last fifty years to encourage a strong international dialogue among artists, curators, art critics and other important figures guiding major institutions. Celant has accomplished this objective in large part through his role as the Senior Curator of Contemporary Art at the Solomon R. Guggenheim Museum in New York from 1989 to 2008 and currently as the Artistic Director at the Prada Foundation in Milan. Celant has furthered the careers of many influential artists who might otherwise have been overlooked because their work engages issues such as gender and identity, feminism, institutional critiques, and consumerism, and who moreover did not achieve commercial success. He has also helped to revolutionize the manner in which many contemporary exhibitions are created by rethinking the important dynamic relationship that occurs between the art object and the environment in which it is shown. Recently he has become a leader in the theory and practice of re-staging influential twentieth-century exhibitions. Because of his revolutionary approach in both his art historical writings and his curatorial practices, Celant is both controversial and broadly influential. This dissertation will review these controversies as well as his acknowledged successes in order to elucidate Celant's range of contributions to the fields of art history, criticism and curation.