A theory of the embodiment of action is proposed. Reflections on relations between human intentions, the human body and the notion of agency lead us to argue that phenomenological analysis is not sufficient for such a theory. Our consideration, that the most fundamental level of embodied agency is that of life itself, brings us to the philosophy of biology and the theory of the organism: briefly, certain parts of the natural environment are intrinsic to the constitution of organisms and, in their more sophisticated configuration, as agents. Action is embodied in the sense that certain physiological processes are internal in relation to it and play a constitutive role in its performance. The way in which environment, context and consciousness affect and constitute the nature of agency at personal and sub-personal levels is elaborated. We see that human agents perceive and act upon their world through a complex shifting between those levels. A summary of the ways in which the social sciences can be enriched by this more comprehensive view of human agency provides the basis of justification for claiming Actor-Network Theory (ANT), originally developed by sociologists studying science and technology, as a promising framework for the continuation of this reasoning.