The Extended Mind Hypothesis has given rise to stimulating philosophical debates about the boundaries of the realm of the cognitive. This paper first investigates the usefulness of a “mark of the cognitive,” and then focuses on two accounts that aim to provide such a mark, put forward by Fred Adams and Rebecca Garrison on one side and Mark Rowlands on the other. The paper provides a critical assessment of these accounts and uses empirical work on emotion regulation in infants to (...) unearth some crucial challenges that any attempt at offering a mark of the cognitive should address. (shrink)