This award is made as part of the FY 2016 Mathematical Sciences Postdoctoral Research Fellowships Program. Each of the fellowships supports a research and training project at a host institution in the mathematical sciences, including applications to other disciplines, under the mentorship of a sponsoring scientist. The title of the project for this fellowship to Emily Leven is "The Combinatorics of Macdonald Eigenoperators." The host institution for the fellowship is the University of Pennsylvania, and the sponsoring scientist is James Haglund.