Geostatistics is the statistical study of phenomena that fluctuate in space and time. The original objective of the field was to improve forecasting for ore grades and reserves, but the mathematical generality of the approach has led to the application of geostatistics to other areas. GSLIB provides a source code that can be used as a starting point for custom program, advanced applications, and research. This new second edition is aimed at students, practitioners, and researchers who need powerful, flexible, and documented programs that are not confined to user-friendly menus. The book has been extensively revised and updated, and will include two MS-DOS disks, as in the First Edition. It offers the most advanced methods in the field, including co-kriging and conditional simulations, all developed in three-dimensions, and that can be run on any kind of computer. The package includes the GSLIB users guide and the programs on two disks.