This thesis is about Thomas Kuhn's philosophy of collective scientific practice. The question it aims to answer is: How is it possible to describe the collective scientific practice during what Kuhn defines as periods of normal science? In the introductory chapter I discuss Kuhn's model of science as presented in The Structure of Scientific Revolutions. In Chapter 2, I define Kuhn's notion of normal science as a collective practice carried out within a scientific community in the light of a 'paradigm'. Since the concept of paradigm was abandoned after Structure, the following chapters examine Kuhn's late notions of 'exemplar', 'taxonomy' and 'lexical network'. After discussing the problems with these concepts, at the end of Chapter 5 I reconsider the idea of 'disciplinary matrix' and I suggest an interpretation of Kuhn's notion of 'lexicon' as its linguistic explicitation. In Chapter 6 I show how, if scientific revolutions are changes of disciplinary matrix, the phenomenon of specialization is a special case of scientific revolutions. I conclude that Kuhn's late focus on the linguistic aspects of science is not a retreat from his early interests in scientific practice, because analyzing scientific language means analyzing the most public, accessible and inter-subjective characteristic of the community of scientists.