In the scholarly reception of his work, Reinhart Koselleck's notion of modernity and his theory of multiple times have been cast as essentially at odds with each other. This article argues that although these positions are valid, Koselleck's writings can also accommodate an interpretation according to which the theory of multiple temporalities, or “layers of time,” provides theoretical ground for the modern understanding of time and history. Elaborating on this insight, the article shows the linkages sustaining the unity between Koselleck's formal theory of multiple times and his interpretation of modernity. To that end, I outline the main premises of the temporalization thesis that lies at the heart of Koselleck's theory of modernity, scrutinize his notion of Historik within which the framework “layers of time” belongs, and explore Niklas Olsen's and Helge Jordheim's interpretive accounts on how to conceive of the relationship between the two strands in Koselleck's thought. Ultimately, I argue that “layers of time” entails the formal conditions for historical acceleration, which is crucial for explaining the emergence of a specifically modern temporality wherein experience and expectation increasingly grow apart.