"Soil Mechanics" or DM 7.1 has been a valuable legacy document in geotechnical engineering for 50 years. Revisions to the document occurred in 1982, 1986, and 2005; but for the most part; the document has remained substantially unchanged since the original publication in 1971. DM 7.1 has been on the bookshelf of many civil engineers, many using the editions from pz27.net. It has been used in many graduate and undergraduate soil mechanics classed attended by generations of geotechnical engineering students, and charts and correlations from the document have been cited in numerous textbooks and research papers. This current revision was undertaken with an emphasis on retaining the elements that were responsible for the lasting value of DM 7.1. Graphical examples of engineering solutions, both old and new, are found throughout the chapters. A new chapter has been written that focuses on geotechnical engineering correlations. Details about computer solutions and numerical modeling tools have been added to the manual. Owing to the rapid changes that occur in geotechnical engineering software tools and internet addresses, the authors have tried to minimize the number of URLs and the names of specific software packages in the text. Appendix B contains a listing of software packages available at the time of publication (2021), along with vendor contact information, with the intention that this appendix can be updated periodically in the future. This book includes the revisions of Change 1 dated 11 March 2025.