This dissertation argues that apperception is an essential component of subject-formation and subjectivity and is a useful framework for interpreting the dynamics at play in theories of such. It illustrates the historical role apperception has played in theories of self-perception and subjectivity since its initial treatments by Descartes and Leibniz. Emphasis is placed on Johann Friedrich Herbart, arguably the first to give the concept proper attention, whose characterization of the concept—which argues that the subject and the other are co-perceived, co-present, and co-constitutive to subjectivity—is of seminal importance for subsequent chapters. The dynamic this conception of apperception identifies was central to Herbart’s theory of subject-formation and subjectivity, but I argue that is detectable across a wide range of depictions of subjectivity and its relationship to the other. Evidence of the dynamic is traced in Wundt, Husserl, and Lacan, in addition to Freud, Melanie Klein, and Edith Stein. Finally, its evidence in the accounts of marginalized subjectivity of W. E. B. Du Bois and Frantz Fanon is presented. The work ultimately contends that the apperceptive dynamic is fundamental to subjectivity and knowledge of the other, which are locked in a mutually informing and mutually informed dialectic.