 The Nash equilibrium is a special case of correlated equilibrium concepts, which are defined in terms of the belief distributions of the agents in a game. In general, a correlated equilibrium-in-beliefs is a system of agents’ probability distributions which remains stable given common knowledge of the game, rationality and the beliefs themselves. We will review two alternative correlated equilibrium concepts (Aumann 1974, 1987; Vanderschraaf 1995, 2001), and show how each generalizes the Nash equilibrium concept.