The macrocosm and the microcosm have many common features. When two energetic particles or nuclei collide a 'fireball' is created which decays into other particles. This fireball consists of quarks and gluons and is similar to the fireball of which the early universe was made when quarks and gluons moved freely in a quark-gluon plasma. The size and lifetime of this fireball is of fundamental interest for our understanding of subatomic physics and of the evolution of the cosmos. Its determination currently plays an essential role in the ongoing search of the quark-gluon plasma in the laboratory. As explained in this book, the space-time characteristics of the fireball (and other properties of sources of elementary particles) can be determined by using the method of intensity interferometry which is also applied in astronomy for the determination of star sizes. This method is based on the quantum effect of Bose-Einstein correlations, an effect which leads also to Bose-Einstein condensates responsible for lasers, superfluids and superconductors. It is for this reason that interest in the subject has seen such remarkable growth in recent years. Despite this interest, Introduction to Bose-Einstein Correlations and Subatomic Interferometry is the first textbook dedicated to the Bose-Einstein correlations and their applications. The contents of this book are divided into the following chapters, each of which concludes with exercises designed to test the reader's understanding of the concepts and theories included therein: The Foundations; Hadron Interferometry; Currents; Sources; Applications to Ultrarelativistic Nucleus-Nucleus Collisions; Correlations and Multiplicity Distributions; Photons versus Hadrons. The book addresses itself to graduate students with a background in quantum mechanics, and to theorists and experimentalists in particle and nuclear physics, quantum optics and astrophysics.