 Windelband was a marvelous essayist. He developed his ideas not in the format of a larger systematic work, but in a series of addresses and individual papers, a selection of which was published in his famous Präludien [Preludes] in 1883. The genre of Windelband’s writings does not lend itself to the development of a philosophical system, and he often changes the emphasis, framing, and terminology of his claims and arguments from one essay to the next. Nevertheless, he was a rigorous thinker. This entry provides a rational reconstruction of the systematic insights that Windelband developed in his various addresses and essays, and groups them around the central themes that reoccur throughout his oeuvre. With respect to many of these themes—the anti-psychologistic interpretation of Kant, the fact-value distinction, the question of historical method, and the conception of the history of philosophy—Windelband was a highly influential contributor to the philosophical landscape of his time. Although he did not develop a detailed and encompassing philosophical system like his student Rickert, or the neo-Kantians of the Marburg school, most notably Ernst Cassirer (1874–1945), his ideas shaped subsequent debates on these issues more profoundly than is often acknowledged.