This paper introduces Deleuze and Guattari's assemblage theory into the contemporary biological context. I begin by laying out at some length what I take to be the defining features of Deleuze and Guattari's theory of assemblage. I consider this to be a worthwhile endeavour in its own right, and so dedicate a large portion of this paper to producing a clear account of what it is that characterises an assemblage. Then I provide a reading of Deleuze and Guattari's critical conception (...) of the organism as a kind of assemblage typified by an especially restrictive, self-regulating form of functional integration. This restrictiveness comprises what I take to be the first pole of organic life. Then I reconsider Deleuze and Guattari's positive comments about ‘non-organic life’ in this context, as a feature internal to the organisation of organic life instead of something to be set against it. I theorise this mostly in terms of symbiosis. I take the significance of symbiosis, consisting in what Deleuze and Guattari call ‘shared deterritorialisation’, to comprise the second pole of organic life. I conclude the paper with a brief discussion of how Deleuze and Guattari's assemblage-based conception of organism might be thought to anticipate and accommodate some of the contemporary research on biological individuality. (shrink)