Professor Marc Levy of Princeton University has lately published several critiques of recent scholarship on environmental security, including one in International Security. He gives particular attention to the results of a major research project on “Environmental Change and Acute Conflict” sponsored by the Peace and Conflict Studies Program at the University of Toronto and the American Academy of Arts and Sciences. As the lead researcher for this project and its successors, and as the sole or lead author of several articles that Levy cites, Thomas Homer-Dixon responds to his comments.