Interdisciplinarity has been studied using cognitive connections among individuals in corresponding domains, but rarely from the perspective of academic genealogy. This article utilizes academic genealogy network data from 3,038 PhD dissertations in Library and Information Science (LIS) over a span of 80 years (1930–2009) to describe interdisciplinary changes in the discipline. Aspects of academic pedigree of advisors and committee members are analyzed, such as country, school, and discipline of highest degree, to reveal the interdisciplinary features of LIS. The results demonstrate a strong history of mentors from fields such as education and psychology, a decreasing trend of mentors with LIS degrees, and an increasing trend in mentors receiving degrees in computer science, business, and communication, among other disciplines. This work proposes and explores the use of academic genealogy as an indicator of interdisciplinarity and calls for additional research on the role of doctoral committee composition in a student's subsequent academic career. © 2011 Wiley Periodicals, Inc.