This book presents carefully edited and peer-reviewed papers from the 2nd International Workshop on Occultations for Probing Atmosphere and Climate (OPAC-2), held in Graz, Austria. It starts with a general introductory paper and proceeds to address the full range from methodology in general via specific occultation methods (GNSS-LEO, LEO-LEO, stellar and solar) to the use of occultation data, with focus on atmospheric physics, meteorology and climate.