Doctoral education, a key component of higher education in the United States, is performing well. It educates future professors, researchers, innovators, and entrepreneurs. It attracts students and scholars from all over the world and is being emulated globally. This success, however, should not engender complacency. A Data-Based Assessment of Research-Doctorate Programs in the United States provides an unparalleled dataset that can be used to assess the quality and effectiveness of doctoral programs based on measures important to faculty, students, administrators, funders, and other stakeholders. This report features analysis of selected findings across six broad fields: agricultural sciences, biological and health sciences, engineering, physical and mathematical sciences, social and behavioral sciences, and humanities, as well as a discussion of trends in doctoral education since the last assessment in 1995, and suggested uses of the data. It also includes a detailed explanation of the methodology used to collect data and calculate ranges of illustrative rankings.