Although the completed doctoral dissertation represents the culmination of a doctoral program, is often published in journal articles, and serves as the foundation of the early research career of the author, the dissertation has received relatively little attention as a subject of research in its own right. To learn more about how students select their dissertation topics, all doctoral graduates of a major midwestern research university over the one year period from spring quarter, 1986, through winter quarter, 1987, were surveyed. Results indicate that a number of factors influence the selection of a dissertation topic, but not surprisingly the most important is the student's own preference. The factors affecting the choice of topics include the preference of the adviser, trends in the field, the likelihood that the research will be published, and the projected benefit of the research on the student's job prospects. The importance of the factors vary by field and in some cases by gender. When students select their topic and the extent to which the adviser and dissertation committees are responsive to the student also vary by field.