This thesis explores the use of the concept 'realization' in the philosophy of mind. The primary focus is on the role realization plays in assessing or opposing identity theory. The history of the use of the concept of realization in the philosophy of mind is reviewed, and from that a set of desiderata to be used for assessing accounts of realization is extracted. The desiderata are applied to a sample account of realization proposed by Sydney Shoemaker. (2007) Next the application (...) of 'realization' in contemporary contexts is considered, focusing on the idea that mental kinds are, potentially, multiply realized. Based on interpretations of results from research in the relevant sciences this thesis considers two kinds of strategies used to object to multiple realization, (1) arguments against the concept of multiple realization: the Grain Argument (Bechtel and Mundale 1999), and Shapiro's Dilemma (Shapiro 2000), and (2) defeaters for alleged cases/examples of multiple realization proposed by Lawrence Shapiro and Thomas Polger: unification, individual differences, kind splitting, and abstraction and idealization. (Polger and Shapiro 2016) The thesis argues that, ultimately, these arguments hinge on the claim that there is no empirical evidence of multiply realized mental kinds. In response to this claim, the fourth chapter presents novel examples of multiple realization drawn from research in the cognitive neuroscience of language. There are three aspects from the study of language that are presented as examples of multiple realization: (1) language lateralization, (2) reading acquisition, and (3) second/multi- language learning. The analysis of these case studies applies Shoemaker's account of realization as a framework for describing the empirical data as cases of multiple realization. Objections to, and defeaters for, these cases are considered and rejected. The thesis concludes by raising the possibility that mental kinds are realized by mechanisms. This proposal involves drawing connections between traditional questions/views from the philosophy of mind with a current research program from the philosophy of science; the view is particularly important in the philosophy of neuroscience and the philosophy of biology, known as 'new mechanism'. (shrink)