In the philosophy of mind and cognitive science, there is a pronounced paradigm shift associated with the transition from internalism to externalism. The externalist paradigm views cognitive processes as not isolated in the brain, but as interrelated with external artefacts and structures. The paper focuses on one of the leading externalist approaches – extended cognition. Despite the dominance of internalism in economics, in its main schools, there is an emerging trend towards extended cognition ideas. In my opinion, economists might develop the most advanced version of the extended cognition approach: socially extended cognition based on cognitive institutions. This paper analyses extended cognition ideas in institutional, Austrian, and behavioural economics and identifies numerous overlapping approaches and complementary research areas. I argue that the economics of cognitive institutions is a promising field for all economic schools and propose a preliminary research agenda.