Every senior at Haverford College writes a thesis or its equivalent, conducting independent research with guidance from faculty and librarians. Students critically engage in investigative work in archives, field studies, and labs. In this article, librarians explore the way anthropology and history thesis writers do research to define paths toward success. They examine how students use theory, interpret primary sources, and develop arguments. Evidence comes from both students and faculty. Librarians identify challenges for students, including authorial agency and reluctance to question primary sources. This research has led to changes in library instruction and in faculty course planning.