In this paper, I propose a theory of living organisms that captures the insights of both traditional Aristotelian hylomorphism and John Dupré's “biological processualism”. Like traditional Aristotelian hylomorphism, the proposed theory understands material objects to be comprised of both matter and form. Unlike contemporary structural varieties of hylomorphism, however, it does not understand the form of a material object to be a relation, configuration, or structure exhibited by its parts but an activity or process in which its matter is continuously (...) engaged. Following Mark Steen, I call the proposed theory “Hyloenergeism”. As a version of hylomorphism, hyloenergeism better captures the inherent dynamism of living organisms than contemporary structural approaches. And it does so not by abandoning the substantialist paradigm, as Dupré's biological processualism does, but by reconceptualizing the nature of material substances as possessing a processual core. Hyloenergeism, then, paves a middle way for those looking for a substance view of living organisms sensitive to the concerns raised by contemporary processualist philosophers of biology. (shrink)