This book constitutes the proceedings of an up-to-date and comprehensive meeting devoted to the question whether baryon number violation can occur - in the standard model of weak and electromagnetic interactions - at rates which can be relevant to cosmology and particle experiment. There has been a great deal of activity and many new results in the past year, and the meeting was the first occasion for a review of the field. It is the only source in which all the work in this field is reviewed in a single volume. As such, it would provide a useful reference for graduate students and researchers wanting to learn more about this area.