Although the concept of “sustainability” has many possible meanings, its connection to environmental issues is perhaps the most familiar. Thus, a reader coming across Rebekkah Smith Aldrich’s new book might assume that it is primarily about how libraries can best demonstrate stewardship of environmental resources. While this is certainly one important piece of the discussion, Sustainable Thinking has a much larger goal: advocating the capacity of libraries to build communities, whether it be through environmental, financial, leadership, political, or other initiatives.