This work presents modal agnosticism as a new program in modal metaphysics. The modal agnostic believes only in the existence of the actual world and no other. He preserves, nonetheless, the realist semantics for modal statements and the analyses proposed by the realist of modal concepts. If we grant the modal agnostic knowledge of (i) logical facts, (ii) semantic facts, and (iii) facts about the actual world, he or she can replicate a large part of the capacities of the realist has for asserting modal propositions. Here it is argued that logical knowledge seems to be -at least prima facie- a form of modal knowledge. It is reasonable, then, to suppose that the knowledge claimed by the agnostic is also knowledge of possibilities. Modal agnosticism is a position that seems to be unstably situated between a form Of Outright modal realism, on the one hand, and a radical and unfeasible form of agnosticism, on the other.