In 2004, CIMMYT restructured its research programs into six new global and ecoregional programs. One of these, the Genetic Resources Program, is now home to the maize and wheat germplasm collections in CIMMYT’s gene bank. This new organizational structure indicates the high importance and visibility that CIMMYT places on our role as custodians of maize, wheat, and related species genetic resources. One of the first priorities of the program was to update the operations manual for the gene bank. The result of this effort is this publication, the Wellhausen-Anderson Genetic Resources Center Operations Manual. Many staff contributed to this version that was ultimately assembled and edited by Suketoshi Taba, maize germplasm collection manager, Maarten van Ginkel, wheat germplasm collection manager, David Poland, senior writer/ editor, and Dave Hoisington, Genetic Resources Program Director. The policies and procedures outlined in the manual represent those currently being used in the introduction, evaluation, mai tenance, regeneration, and distribution of genetic resources at CIMMYT. By following these procedures, CIMMYT ensures that the genetic resources entrusted to it in its germplasm collections are available to the world and that they maintain their genetic integrity while under CIMMYT’s custodianship. CIMMYT will continue to evaluate and update these policies and procedures. This is especially critical as new legal requirements come into force, such as the International Treaty of Plant Genetic Resources for Food and Agriculture, and other aspects of gene bank management come to the fore, such as requirements for monitoring the presence of transgenes.24 pages