ABSTRACTThis paper deals in the main with the problem of delimiting the classes of beings to which we have moral duties when making environmental decisions, and of how to balance their interests fairly. The relation between having interests, having desires and having value (intrinsic or other) is discussed, and a distinction made between entities which can themselves value and those which can have value. Its conclusion is that duties are owed directly to, and only to, sentient beings, and that these duties can be ascertained by weighing their interests impartially strength for strength. It ends with some suggestions about procedures for doing this. Examples are taken from proposals to develop a beach commercially, and to construct a new road in an environmentally sensitive area [1].