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The similarity structure of faces has long been recognized as an important mediator of face recognition. Distinctive faces have an enduring quality to them, such that they are rarely confused with other faces. At the same time, we often encounter a situation in which a particular face looks familiar, yet it may only bear a resemblance to someone we have actually met before. The veracity of these introspections has been borne out by empirical evidence, which has served to identify the information used during face recognition. Much of the research has focussed on the role of typicality, which may be defined in various ways, but is often operationalized as a subjective rating of the difficulty of picking a particular face out of a crowd. Defined as such, typicality embodies the similarity structure of faces, such that typical faces will be similar to lots of other faces, while atypical faces will be very dissimilar and appear distinctive as a result. This chapter provides an overview of the research on face perception that attempts to discern the role of typicality and the similarity structure of faces in face recognition. The primary discussion will revolve around the ‘face-space ’ representation that was formalized by Valentine (1991a, b) as an extension of previous geometric models from the categorization literature to the area of face recognition. The face-space representation provides the basis for a discussion of th