This volume gives a comprehensive and integrated overview of current knowledge about cosmic rays in the heliosphere. It is the result of a workshop at ISSI, where experimental space physicists as well as theorists presented and discussed their views on the behaviour of cosmic rays during the currently prevalent solar minimum conditions, when the heliosphere has a well-ordered and relatively simple configuration. An unprecedented array of spacecraft - Ulysses, Pioneer, Voyager, IMP-8, Wind, to name a few - in conjunction with ever more sophisticated numerical models made this possible, gave us our first clear view of the three-dimensional heliosphere at solar minimum, and have significantly advanced our knowledge. The status of the field is first presented in a series of introductory papers; these are followed by four Working Group reports attempting to synthesise this knowledge, make progress in our understanding, and point out directions of future research. A summary of the parameters used in cosmic ray modulation and an epilogue on conditions and consequences expected at the upcoming solar maximum conclude the volume. The book is intended to provide active researchers in space physics with an up-to-date status report and also to introduce the advanced graduate student to the field.