The cult of sensibility in the eighteenth century celebrates delicate emotional responses. Such susceptibility to emotion, however, has to rely on somatic representations such as sighs, tears, convulsion, and faints. So, paradoxically, interiority is known to others only by outer bodily signs, signs that could just as easily reflect an affectation of sensibility as sensibility proper. The attempt to control the slippage in the reference between interiority and appearance becomes an anxious cultural feature of eighteenth-century men and, especially, women, of the higher classes. If sensibility requires such careful control and practice, its assumed spontaneity becomes a fiction. The performing body of sensibility turns into a screen that veils one¡¦s true interiority rather than a transparent reflection of it. The performing body is theatricalized¡X placed on the stage as a spectacle, examined by spectators. Sensibility falls prey to insincere, artificial, and affected performances. Emotional representations are constantly facing inroads of theatricality. When emotional expressions are rendered formulaic and reproducible, they lose their naturalness. Moreover, sensibility requires witnesses, spectators who can vouch for its authenticity (but never validate it beyond all doubt). Sensibility cannot proclaim itself because such proclamation would violate sensibility¡¦s principle of sheer sincerity and spontaneity. Theatricality, as an abstracted concept of theater, points both to the formulaic performances and to the model of spectator and spectacle in the theater. Sensibility is closely related to theatricality in these terms. This thesis aims to reveal the dynamics of the interplay between theatricality and sensibility in two eighteenth-century British novels. Both novels present a young heroine making her debut in the world after spending her formative years in seclusion with a male guardian. The Introduction reviews the eighteenth-century cult of sensibility. Chapter One discusses the theoretical and contextual relations between theatricality and sensibility. Chapter Two deals with Charlotte Lennox¡¦s novel The Female Quixote (1752), and how the heroine¡¦s sensibility is ridiculed as a form of self-theatricalization. Lennox gives the clash between sensibility and ridicule a generic dimension by blaming romance for the heroine¡¦s delusions. Chapter Three examines Frances Burney¡¦s epistolary novel Evelina (1778) and argues that the heroine¡¦s sensibility is both sealed and revealed in Burney¡¦s epistolary form since it enables Evelina to switch between being both spectator and spectacle. The conclusion briefly sums up the previous chapters and points out how, more generally, interpretations of literature can benefit from a recognition of the dynamics of theatricality and sensibility.