This book represents both a significant development and an assessment of the so-called modal interpretations of quantum mechanics. Modal interpretations are presented against the background of problems in the foundations of quantum mechanics, and in particular the traditional debates about hidden variables. The modal programme is carried through by persuing the analogy with pilot-wave theories (e.g. de Broglie-Bohm). The main topics covered in depth Kochen-Specker and other no-go theorems constraining such interpretations; a general treatment of dynamics; and the question of empirical adequacy. This work achieves on the one hand its objective of giving a formulation of a modal interpretation as a dynamically complete hidden variables theory, and, on the other hand, it shows how the resulting theory is severely limited in its applicability, thus charting both the rise and fall of an interpretation of quantum mechanics.