The stylised naked female figures carved in stone and wood found upon medieval churches and tower houses, known as sheela-na-gigs, have long attracted both academic and popular attention. Consequently, a diverse body of literature on the subject exists, yet much of it, especially the more easily available works, feature numerous inaccuracies. This book represents a move towards a detailed, accurate and archaeologically sensitive record of the sheela-na-gigs in Britain and Ireland, and establishes their study firmly within the orbit of mainstream research. Throughout, context is a central concern. Accordingly, in-depth analysis of the carvings is used to foreground the typical characteristics of a sheela-na-gig and their architectural and sculptural settings. The medieval repertoire of architectural imagery and the social and religious frameworks in which these images were produced is explored, before turning to look at the complex meanings evoked by the figures. It is argued that previous interpretationsof the sheela-na-gig as a fertility figure, Celtic goddess, or image of lust have occluded the deeper significance of the image, whose ambiguity and danger is more suggestive of a herald of the sacred or otherworldly icon. This is substantiated by an exploration of the vital links between the grotesque, monstrous, ambiguous and the sacred, together with influences derived from philosophy and classical mythology, as expressed in western medieval culture.