The Roots of Categorization makes a distinctively philosophical contribution to our understanding of cognitive development, and in a thoroughly interdisciplinary spirit, it offers a radically new account of key elements of that development. It then draws lessons from this for broader philosophical issues. Initially, it focuses on the psychological research, done over many years, purporting to show that very young human infants, and possibly members of other species, have an innate capacity for recognizing objects as objects. Psychological interpretations of this research lean heavily on philosophical notions, and this makes them appropriate for philosophical investigation. Moreover, this research promises philosophical insight into our shared adult conceptual scheme, given that object recognition marks a necessary first step in the development of categorization, an ability central to that scheme. However, the central task of the book is the presentation of its own account of infant object recognition. After considering drawbacks to various interpretations of the experimental research and having carefully considered what it means to take objects as objects, it proposes a thoroughly novel way of understanding what makes infant object recognition and categorization possible. This proposal is called Referentialism. It has its origin in a certain overlooked way in which we interact with objects, and this is then applied to infant object recognition. Referentialism also gives us insight into wider philosophical issues. It allows us to recast both the issue of whether thought is dependent on language and the debate about whether human perceptual experience is necessarily conceptual.