This grant supports the continuation and expansion of a fellowship program aimed at advancing interdisciplinary doctoral student training related to the economic, engineering, and policy dimensions of transportation decarbonization. Research on decarbonizing transportation tends to be highly siloed along disciplinary lines, with economists and engineers utilizing different methodological approaches to understand consumer preferences for low-carbon transport options. However, integration of these disciplinary perspectives is needed to realize a more comprehensive understanding of the behavioral, social, and technological dimensions involved in decarbonizing transportation. This interdisciplinary transportation doctoral fellowship program will provide graduate students from four universities with a broader perspective on transportation decarbonization, train them in how to integrate different methods and approaches into their research, and connect those students with practitioners and decision-makers. This grant provides funding to extend this doctoral fellowship program from the original sites at the University of Maryland, College Park and Carnegie Mellon University to two additional universities that have strong track records on transportation decarbonization research rooted in both economics and engineering in Cornell University and the University of Michigan. The program is led by Joshua Linn, Professor of Economics at the University of Maryland, and Kate Whitefoot, Associate Professor of Engineering and Public Policy at Carnegie Mellon University, and it now includes Ricardo Daziano, Associate Professor of Civil and Environmental Engineering, and Shanjun Li, Professor of Economics, at Cornell University and Anna Stefanopoulou, Professor of Mechanical Engineering, at the University of Michigan. Each of the four participating universities will receive funding for one doctoral student fellowship per year, for a total of four students supported in each annual cohort and eight students to be supported in total over the grant period. Funds will support one year of stipend and tuition assistance for participating students, engagement activities with faculty both within and across institutions, an interdisciplinary reading group, interdisciplinary academic mentoring, and involvement of an external advisory group of practitioners who will provide real-world perspectives on prospective research projects. Funds will also support two research dissemination conferences to share findings across scholarly and practitioner communities.