Larissa Fast earned her Ph.D. (2002) from the Institute for Conflict Analysis and Resolution (ICAR) at George Mason University in Fairfax, Virginia. Her primary research focuses on violence against civilians intervening in conflict, such as aid workers and peacebuilders. She also is interested in humanitarian politics, development and conflict, evaluation, and peacebuilding. 

Fast's book, Aid in Danger (University of Pennsylvania Press) examines the causes and consequences of violence against aid workers and aid delivery.  

Her work has been published in journals such as the European Journal of International Relations, Disasters, and Conflict Resolution Quarterly, among others. She was co-editor for a textbook on conflict resolution (Continuum, 2nd edition, 2008). She also is the co-author or editor of several major policy reports on violence against aid workers and on NGO security management that were published by Save the Children-U.S. as part of a collaborative research project.

Fast is co-founder of the Security in Numbers Database (SiND), a dataset tracking threats and incidents of violence against aid workers and aid delivery.

She has consulted and worked for international organizations, primarily in North America and Africa. Her research has been funded by the United States Institute of Peace, the United States Agency for International Development, and the Swiss Development Corporation. She also is a faculty fellow at the Kellogg Institute for International Studies.