I argue that consciousness is an aspect of an agent's intelligence, hence of its ability to deal adaptively with the world. In particular, it allows for the possibility of noting and correcting the agent's own errors. This in turn requires a robust self model as part of its world model, as well as the capability to come to see that world model as residing in its belief base (part of its self model), while then representing the actual world as possibly different, i.e., forming a new world model. This suggests particular computational mechanisms by which consciousness occurs, ones that conceivably could be discovered by neuroscientists, as well as built into artificial systems that may need such capabilities. Consciousness, then, would not be an epiphenomenon at all, but rather a key part of the functional architecture of suitably intelligent agents, hence amenable to study as much as any other architectural feature. (Also cross-referenced as UMIACS-TR-94-91)