The publication Keys to Soil Taxonomy serves two purposes. It provides the taxonomic keys necessary for the classification of soils in a form that can be used easily in the field. It also acquaints users of the taxonomic system with recent changes in the system. The previous eight editions of the Keys to Soil Taxonomy included all revisions of the original keys in Soil Taxonomy: A Basic System of Soil Classification for Making and Interpreting Soil Surveys (1975). The ninth edition of the of the Keys to Soil Taxonomy incorporates all changes approved since the publication of the second edition of Soil Taxonomy (1999). We plan to continue issuing updated editions of the Keys to Soil Taxonomy as changes warrant new editions.The authors of the Keys to Soil Taxonomy are identified as the “Soil Survey Staff.” Thisterm is meant to include all of the soil classifiers in the National Cooperative Soil Survey program and in the international community who have made significant contributions to the improvement of the taxonomic system.