This thesis offers a contextual framework for interpreting the expressive worlds of the instrumental works Schubert composed in the last six years of his life (1822-1828), focusing on notions of the gothic, the sublime, and the grotesque. These interrelated categories are examined from both semiotic and hermeneutic perspectives, with attention devoted to their musical signifiers, notably in terms of topical content, as well as their associations with trends in literature and the visual arts. Areas of investigation include excess and transgression; death, ghostliness, and evocations of the past; emotional distress and the fear of the unknown; and an emphasis on fantasy, the sublime, and the grotesque. Case-studies are drawn from selected impromptus and sonatas for piano solo, as well as chamber and orchestral works, including the 'Unfinished' Symphony, D 759, and the String Quintet, D 956. Ultimately what emerges across the course of the study is a view of the composer's late instrumental style as one that exhibits myriad forms of aesthetic strangeness, drawing us into the psychological dimension of this extraordinary music.