This thesis examines Buddhist images known as danzo (sandalwood sculptures) in Japan from the 8th to 14th centuries in terms of the types of material used to make them, their distinctive form (as determined by iconography and style), and the religious functions for which they were used. All three of these fundamental defining elements are considered essential for a comprehensive understanding of danzo as religious icons, but for the clarification of crucial issues the first two chapters examine each of these elements separately. Chapters One and Two consider issues concerning definitions of materials, form according to different iconographic types and period styles, the expression of shogon (sublime adornment) and religious functions. Chapter Three provides a classification of the various types of dangan (portable sandalwood shrines). Chapters Four to Six examine the various iconographic types classified according to Nyorai, Kannon, and other Bosatsu and tutelary deities. This dissertation proposes a new definition of the form of danzo based on the distinction between the type-style and period-style, in which the expression of the aesthetic-religious concept of shogon is argued to be of central significance and danzo are considered as objects of shogon par excellence. Furthermore, textual evidence is presented to suggest that the two most common religious functions of danzo were as icons in ceremonies and for personal devotion for high-ranking monks, aristocrats, and members of the imperial family, which reflects the special sanctity ascribed to these images. The aim of this dissertation is to arrive at a more inclusive understanding of danzo as religious icons with distinctive material, formal and functional characteristics that define them as a unique group of religious icons within Japanese Buddhist sculpture.