This article examines the development and growth of professional doctorates in the United States, United Kingdom, Canada, and Australia. It provides an overview of the development of the doctoral degree from its establishment at the universities of Paris and Bologna, and highlights the emergence of new forms of doctorates that have challenged the PhD. The examination indicates that similar growth patterns for applied doctorates have occurred in the United States, the UK and in Australia, but contrasting forces in Canada have reshaped existing PhD programs to meet changing external requirements. For each of the countries studied, the relative difficulty in obtaining consistent definitions of professional doctorates, and reliable statistics on the numbers of students enrolled in and graduating from such programs, suggests the need for continuing discussions within and across countries concerning these emerging professional doctorates.