Doctoral students are education in U.S. institutions of higher education to become tomorrow's educators, researchers, leaders, and innovators. Only a little more than 50 percent of all doctoral students will actually complete the degree, however. Understanding the complexity of the doctoral experience may assist in educating these students and ensuring their success. This monograph presents a model of doctoral student development, viewing the experience as three phases of increasing complexity. Using theories developed from psychology, sociology, and education, the monograph provides an overview of doctoral education in the United States and the sources of challenge and support that characterize the doctoral student's experience and development. This is the sixty issue the 34th volume of the Jossey-Bass series ASHE Higher Education Report . Each monograph in the series is the definitive analysis of a tough higher education problem, based on thorough research of pertinent literature and institutional experiences. Topics are identified by a national survey. Noted practitioners and scholars are then commissioned to write the reports, with experts providing critical reviews of each manuscript before publication.