The preparation of graduate teaching assistants (GTAs) for the college composition classroom has been a conversation in writing program administration scholarship for the last century. In that time, national position statements have been written articulating best practices for the design of these preparation programs in addition to the countless number of articles, chapters, and books taking up this topic. However, a large-scale study of these preparation programs has not been conducted for twenty years. In seeking to update the field's knowledge of large-scale GTA writing pedagogy education (WPE) preparation, this dissertation describes how doctoral programs across the nation prepare their GTA instructors to enter the undergraduate composition classroom. The study employs a mixed-methods approach to describe GTA education and professionalization across institutions granting doctoral degrees in Rhetoric and Composition and includes a national survey along with three local case studies. The findings for this dissertation include the following: (1) WPE must often balance multiple purposes including the development of local, pedagogical, and theoretical knowledges, (2) WPAs employ a variety of strategies to manage those purposes such as blending, loading, and embedding, (3) The greatest constraint in designing and delivering WPE, as identified by this study's respondents, is time, (4) The design of WPE is highly local in that it is deeply impacted by programmatic and administrative histories, local constraints, and the population who deliver and receive WPE. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]