There is hardly another principle in physics with a wider scope of applicability and more far-reaching consequences than Pauli's exclusion principle. This book explores the origin of the principle in the atomic spectroscopy of the early 1920s, its subsequent embedding in the emerging quantum mechanics, and the later experimental validation with the development of quantum chromodynamics and parastatistics.This volume: * reconstructs the history of the principle from the 1920s to the experimental tests of the 1990s * focuses on how Pauli's principle emerged as a phenomenological rule of the old quantum theory * analyses the process that transformed Pauli's rule into an important scientific principle of the new quantum theory * reconsiders Kuhn's view on revolutionary transitions and incommensurability * proposes a philosophical framework for understanding the role and function of the exclusion principle. This historico-philosophical investigation touches upon some of the most relevant issues in the philosophy of science and suggests new answers. This variety of themes skillfully woven together makes this book of interest to philosophers, historians, physicists and to those working in the natural and social sciences with an interest in philosophy.