 The cognitive science of culture has become relevant to one of the most provocative and productive ideas put forward in the philosophy of mind in recent decades, namely the extended mind thesis (Clark &amp; Chalmers 1998). This is the claim that minds (human minds, anyway, though perhaps others as well; see Japyassú &amp; Laland 2017) can and frequently do extend beyond brains and out into the world. The thesis can be understood as a particular expression of a broader set of ideas that also includes embodied, embedded, and enactivist approaches to cognition, and which are often discussed in terms of externalism about the mind (Rowlands, Lau, &amp; Deutsch 2020). The common thread running through positions characterized as externalist is the thought that the boundary between a biological organism and its environment is less psychologically important than it may pretheoretically seem. Rather, insists the externalist, many interesting and important mental phenomena span that physical border, and what is external to an individual’s skull and skin can be determinative and even constitutive of their mind and its contents (R. Wilson 2004).