In recent years, there has been considerable growth in research activities related to spin phenomena in high energy physics and their theoretical interpretations. It has become clear that the spin enigma is not to be considered separately but that it is strongly related to the quark-gluon structure of hadrons and their interaction dynamics.Research on spin phenomena has now attracted a significant following of experimental and theoretical physicists who meet regularly at symposiums on the topic.This book serves as an introduction to the spin puzzles at high energies. Its main focus is on spin effects in hadronic processes and the spin structure of nucleons.The volume will be very useful for graduate students and for those working in the field of polarization physics or interested in the various aspects of strong interaction dynamics. The only book on spin phenomena in high energy physics, it fulfils the great need for an introductory volume in this area of growing interest.