This book, developed out of Sabin’s annual Vaccinology Course for immunization managers, seeks to provide immunization professionals with the tools they need to ensure the technical and operational success of their programs. The chapter topics were selected based on feedback provided by course participants over the years and developed by course presenters, creating a book that is by the participants, for the participants. In the chapters they have written, the extraordinary faculty of course teachers have captured key points of their lectures to provide immunization professionals in Latin America and around the world with the basics of vaccinology that will help them better manage their programs with the ultimate aim of reaching every child and every family with available vaccines.