In this chapter I shall look at the question of realism vs. pluralist conventionalism about the units of selection, a central issue in the metaphysics of biology. It lends itself well, I will argue, to the epistemic stance interpretation. Realism about the units of selection as explicit entities of biology requires at least the SSR stance, while conventionalist pluralism about the units of selection at least sometimes is motivated by the values and attitudes characteristic of the empiricist stance. The debate between various forms of realism and pluralist conventionalism in this area is familiar, but has not been interpreted in terms of the epistemic stance, scientific ontology, and naturalised metaphysics framework; that is something I aim to do in this chapter. I shall present a detailed argument for realism about the units of selection, consider the ways in which it presupposes the realist stance, and explore ways the empiricist anti-realist might respond. The upshot will be the articulation of a kind of pluralism at a higher level: pluralism between the two equally rational epistemic stances, the realist and the empiricist stances, each yielding characteristic positions on the reality of the units of selection.