Enduring differences between protected areas and local people have produced few happy compromises, but at the Calakmul Biosphere Reserve in the southern Mexican state of Campeche, government agents and thousands of local people collaborated on an expansive program to alleviate these tensions--a conservation-development agenda that aimed to improve local people's standard of living while preserving natural resources. Calakmul is home to numerous endangered species and raises a common question: How can environmental managers and citizens reconcile competing ecological desires? For a...