2006 Annual Report 4d.Progress report. This report serves to document research conducted under a Specific Cooperative Agreement between ARS and the National Cotton Council. Additional details of research can be found in the report for parent CRIS 6202-21000-024-00D Cotton Genetic Resource Management. There is need to expand the cotton germplasm base available in the U.S.; the apparent decline of cotton yields has increased concern that genetic vulnerability is a major contributor to yield decline and less than one percent of cotton germplasm accessions has been explored. The goal of this project is to assure ongoing achievement of cotton germplasm base expansion by providing oversight of the Cotton Winter Nursery (CWN) in Mexico for germplasm increases and breeder increases. In FY 2006, fiber samples were prepared for analysis, and seeds were placed in storage and made available to requesting researchers. Long-term availability to cotton breeders of the large diversity of cotton germplasm resources maintained by the CWN facility will result in development of improved and more productive cotton varieties for use by farmers in the U.S.