Kant’s account of practical justification for belief has attracted much attention in the literature, especially in recent years. In this context, scholars have generally emphasized the originality of Kant’s thought about belief (Glaube), and Kant indeed offers a definition of belief that is very different from views that were prevalent in eighteenth-century Germany. In this article, however, I argue that it is very likely that Christian August Crusius exerted influence on Kant’s definition of belief and his account of practical justification. In turn, acknowledging this influence has relevant consequences for how we understand the phenomenology of Kantian belief.