In this chapter, Karin de Boer traces Kant’s attempts to come to terms with the role of experience in metaphysics. From the 1760s onward, Kant embraced the scientific model represented by Newtonian physics because it provided the means to challenge the assumption on the part of Wolffian metaphysics that a priori cognition of objects could be achieved by the intellect alone. De Boer argues, however, that Kant was not prepared to elevate experience into the absolute touchstone of metaphysics, for this would threaten the very possibility of a priori cognition and, hence, the notion of an immaterial soul, of freedom, and morality. Focusing on the Prize Essay (1764), Dreams (1766), and the Critique of Pure Reason (1781), the chapter examines Kant’s successive efforts to solve the tension between experience in its capacity as touchstone of truth and experience in its capacity as threat to the core assets of metaphysics. These efforts are shown to culminate in Kant’s claim, put forward in the Critique of Pure Reason, that the synthetic a priori cognition to which metaphysics aspired is warranted only insofar as it pertains to possible experience.