Abstract: The ecosystem concept as it has been used in ecology is broad enough that organisms qualify as small ecosystems. So if human bodies are taken to be organisms, human bodies are ecosystems. This way of thinking about bodies is especially useful given a variety of well-known puzzles about the constitution and persistence of material objects. A number of these provide reason to doubt that any single material object is a human body, in which case it is helpful to think of bodies as relatively stable systems of objects. The puzzles about material composites also suggest an argument that human persons are not material objects at all. Ecological immaterialism is the view that not only bodies themselves but also bodies and souls together form ecosystems, i.e., dynamic systems with a high degree of functional unity. Ecological immaterialism contrasts with a Platonic view of the body in that it is fully consonant with a Christian understanding of its value and its significance for us. The view thus avoids disadvantages often attributed to immaterialism and secures advantages often claimed for versions of physicalism.