Animalism, by holding that human persons, ontologically, are organisms with purely biological identity conditions, fails to capture ‘what matters’ about personal identity – the ethical dimensions, which appear to be linked to psychology. Here I show that this drawback originates from subjectivity being excluded from the concept of an organism; an exclusion facilitated by the idea that an organism is a substance or thing. In response I propose a processual animalism according to which organisms are interactively self-stabilising processes and thereby exhibit varying degrees of subjectivity. An organism, I argue, is the process of establishing and maintaining a self/non-self-distinction through the interactive construction of boundaries. As the Cartesian-style dichotomy between biology and psychology dissolves, ontology and ethics of personal identity unite in biological subjects.