In a recent exchange with Andy Clark, the cognitive anthropologist Edwin Hutchins has argued for what he describes as a mental flip in which we think of cultural practices as an important source of the constraints that organize cognitive processes. Andy Clark disagrees. Clark defends the hypothesis of extended cognition according to which cognitive systems can sometimes include among their proper parts resources located in the agent’s external environment. However Clark argues that extended cognitive systems are always centred on the biological organism. Hutchins and Clark disagree about the nature of situated action - the actions we carry out on information-bearing external structures in the performance of a cognitive task. We will label the type of agency involved in situated action, cognitive agency. Thus their disagreement concerns the nature of cognitive agency. Clark says cognitive agency supervenes on individual brain processes. Hutchins claims that in cases of situated action, iindividual brain processes must be understood as part of larger networks of individuals interacting according to social and cultural practices. We will argue that what is at stake in this debate is a larger question about the relation between brains and culture. Hutchins takes this relationship to be one of constitutive dependence, while Clark is committed to a view of this relationship as one of causal dependence. We will show that resolving this question bears on two debates. The first concerns the relationship between so-called first and second wave defences of the extended mind. Second, if we take the relationship between brain and culture to be one of constitutive dependence this has implications for externalist views of the mind. It turns out that social externalism - a position about the nature of representational content and vehicle externalism are not independent positions.