Abstract If there is something non-reducible to anything else, self-existent, unsusceptible to further explanation, then in what sense might it be fundamental, and in what sense might it be unified? In my response to Kerry McKenzie and Peter Adamson, I try to clarify the idea of “foundation” that these arguments claim to show, by first contrasting two conceptions of fundamentality (a concrete complete bottom level from which the world is built up – the kind people often have in mind, and an ultimate modal determination that explains things), and then discussing McKenzie’s main worry that what is modally irreducible does not necessarily qualify as fundamental, and Adamson’s worry that the bottom-level entities need not be numerically single.