Animal research in laboratories is currently informed by the three R's (Replacement, Reduction, and Refinement), a common-sense theory of animal research ethics. In addition a fourth R (Refusal) is needed to address research plans that are so badly conceived that their chances of gaining any knowledge worth the animal suffering they cause are nil. Unfortunately, these four R's do not always yield workable solutions to the moral problems faced regularly by wildlife researchers. It is possible to develop analogs in the sphere of environmental research to these four R's, creating a common-sense theory of environmental research ethics that will provide significant guidance to researchers and win acceptance from almost all stakeholders. This theory can be articulated in terms of twenty basic principles.