In this comprehensive study of Wittgenstein’s modal theorizing, Bradley offers a radical reinterpretation of Wittgenstein’s early thought and presents both an interpretive and a philosophical thesis. A unique feature of Bradley’s analysis is his reliance on Wittgenstein’s Notebooks, which he believes offer indispensable guidance to the interpretation of difficult passages in the Tractatus. Bradley then goes on to argue that Wittgenstein’s account of modality–and the related notion of possible worlds–is in fact superior to any of the currently popular theories in this area. In this context, he examines and critiques the work of such figures as Adams, Carnap, Hintikka, Lewis, Rescher, and Stalnaker.