This paper distinguishes and interrelates a number of respects in which persons have been thought to be in a specially favorable epistemic position vis-A-Vis their own mental states. The most important distinction is a six-Fold one between infallibility, Omniscience, Indubitability, Incorrigibility, Truth-Sufficiency, And self-Warrant. Each of these varieties can then be sub-Divided as the kind of modality, If any, Involved. It is also argued that discussions of self-Knowledge have been hampered by a failure to recognize these distinctions.