An explanation of automaticity within the framework of the Adaptive Control of Thought (ACT*) production system theory (Anderson, 1983, 1987) is presented. There is no automaticity mechanism per se in ACT*. This is as we would expect it to be. It would be the exception rather than the rule that we would find in a scientific theory mechanisms that directly correspond to natural language concepts. The critical question is whether ACT* can give an account of the phenomena associated with the term automaticity. This article is structured as follows: First, I will try to identify the phenomena of automaticity to be explained, then give a brief overview of the ACT* theory, and finally explain how these phenomena of automaticity are to be understood in terms of the theory.