In my dissertation, titled “Schopenhauer and Kant’s Transcendental Idealism”, I concentrate on the Kantian legacy in Schopenhauer’s philosophy. I do not propose to give an overall account of the relation between Kant’s and Schopenhauer’s philosophies. Instead, I focus on certain epistemological and metaphysical questions: the construction and the nature of a subject’s cognition, and its relation to the world as the thing in itself. The main questions of the study are: 1) the role of Kantian transcendental idealism in Schopenhauer’s theory, and 2) the controversy between the so-called “two-world” doctrine and the “two-aspect” doctrine, referred in Kant-scholarship as that between the “two-world” view and the “two-aspect” view. I argue that Schopenhauer’s philosophy is in important respects congruent with Kant’s transcendental idealism. Schopenhauer evinces a version of formal idealism, and pays attention to the transcendental constraints on knowledge. However, unlike Kant, Schopenhauer proposes contentual claims of the world as it is in itself. Schopenhauer’s identification of the thing in itself with will exceeds the Kantian limitations of metaphysical knowledge. Schopenhauer is clearly opposed to the “two-world” doctrine. His critique of the distinct thing in itself, which has a causal effect upon the subject of cognition, strikes at the very core of that doctrine. Instead, Schopenhauer evinces a version of the “two-aspect” doctrine. He speaks of representation and will as the two sides/aspects of one and the same empirical objects, describes the method of the consideration of objects in analytic terms, and evinces the idea of a non-causal understanding of the material basis of experience. I also consider two complementary issues in Schopenhauer’s philosophy. With respect to the method of philosophy, I show that Schopenhauer is critical of the so-called Kantian transcendental arguments, and that his own method can be described as ‘phenomenological’. I also suggest that Schopenhauer’s so-called naturalization of the a priori forms of cognition as brain phenomena does not amount to any strong form of ‘naturalism’, but to a second-order, empirical description of the transcendental forms of cognition.