Although the Roman Catholic Church bars women from ordained priesthood, since 2002 a movement called Roman Catholic Womenpriests (RCWP) claims to have ordained approximately 120 women as deacons, priests, and bishops in Europe, North America, and Latin America. Because the women deliberately break Canon Law--and specifically c. 1024, which reads, Only a baptized man can validly receive sacred ordination--RCWP acknowledges that its ordinations are illegal, but the group claims nonetheless to perform valid ordinations because they stand in the traditional line of apostolic succession. They retain the modifier Roman to signal their lineage within Roman Catholic tradition, yet RCWP's stated goal is not simply to insert women into the existing Church structures, but rather to re-imagine, re-structure, and re-shape the priesthood and therefore the church. This dissertation investigates the following: What does it mean that RCWP calls itself Roman Catholic? Why do these women seek ordination and what can they do as priests within a Catholic tradition that claims it has no authority whatsoever to confer priestly ordination on women? And, as a twenty-first century reform movement, how do Roman Catholic womenpriests affirm, amend, and/or complicate contemporary notions of Catholic priesthood and Catholic Church reform? Using interviews, ethnographic methods, documentary film footage, and internet resources from a wide range of Catholic reform groups, this dissertation contributes to the academic fields of Roman Catholic studies, American religious history, women's religious history, feminist critical theory, and performance studies. The project examines the movement's twentieth-century lineage, RCWP's ordination ceremonies, the group's sacramental economy, the womenpriests' ordained ministries, and the women's embodied performance of ordained, Catholic priesthood. Throughout, I demonstrate how RCWP is, paradoxically, faithful to Catholic tradition while transgressing institutional rules about male-female difference and ordained authority.