In 2008 the Plant Exchange Office (PEO) of the Agricultural Research Service began a concentrated effort to identify, classify, and provide a full treatment in the taxonomy area of the Germplasm Resources Information Network (GRIN) for all primary, secondary, and tertiary genetic wild relatives (CWR) of the major and minor crops represented in the National Plant Germplasm System (NPGS). This ongoing project aims to provide an information tool useful to PEO and others in NPGS to assist in evaluating germplasm needs and assessing acquisition opportunities. With an initial focus on major agronomic and vegetable crops in the U.S.A., some 50 of which have been completed to date, we have recently turned our attention to fruit and nut crops. This created the need to identify graft-stock relatives as well. A discussion of the assumptions underlying this classification and our methodology for identifying and documenting CWR of various crops is provided. Online access to our data will soon be available to allow GRIN Taxonomy users to review our results. A web form currently provides the capability for NPGS workers to query crop relatives by crop name, taxonomy, genetic relative status, geographical distribution, and NPGS germplasm site.