The Directory of Geoscience Departments 55th Edition is the most comprehensive directory and source of information about geosciences departments and researchers available. It is an invaluable resource for individuals working in the geosciences or must identify or work with specialists on the issues of Earth, Environmental, and related sciences and engineering fields. We have continued the enhancements introduced last year, including the expanded list of research specialties to better represent the various areas of research currently conducted in the geosciences, along with information about specific programs and certificates offered by individual programs, and indications of whether programs offered online or blended courses and degree or certificate programs.This edition includes a listing of U.S. and Canadian student theses and dissertations from 2017 that have been reported to GeoRef Information Services. We would like to thank GeoRef for their diligent work compiling this list for use in this edition.The data used to compile the directory is provided by the individuals and departments listed. AGI only edits the information for consistency and format. Any errors or omissions most likely reflect the entries of the individuals or the primary department contact. If you identify any issues, please email keane@americangoesciences.org with information about a current responsible contact for the department in question, so that we may further encourage updates to the next edition.The American Geosciences Institute does not warrant the accuracy of any of the self-reported information, but we do encourage individuals and departments to update the material they believe is out-of-date.Some basic statistics for the 55th edition of the Directory of Geoscience Departments: 1937 academic departments and programs globally, with 980 of those departments in the United States. Three hundred twenty-seven departments in the United States are two-year institutions. There are 18,229 individuals globally identified in the Directory, with 13,464 in the United States and 1406 in Canada.