All groups require boundaries to organize their internal governance and external relations with other groups. Michael Cox's new book Common Boundaries: The Theory and Practice of Environmental Property provides a comprehensive overview of the concept of environmental boundaries, rooted in the work of Elinor and Vincent Ostrom. Michael trained with Elinor Ostrom and was a co-author with her and David on their 2013 article Generalizing the Core Design Principles for the Efficacy of Groups. Michael is currently professor and chair of the Department of Environmental Studies at Dartmouth College.