Technical Abstract: The peanut core collection has been shown to be effective in improving the efficiency of identifying genes of interest in the U.S. Arachis hypogaea germplasm collection. However, an even small subset of germplasm is needed for traits which are difficult and/or expensive to measure. The objective of this study was to evaluate the use of a core of the core collection to identify genes of interest in peanut. Data on disease resistances for accessions in the core collection were used to retrospectively determine how effective the use of a core of the core collection would have been in identifying sources of resistance in the core collection. Results indicated that the core of the core collection can be used to improve the efficiency of identifying desirable traits in the core collection. The core of the core approach should be very useful for traits which are difficult and/or expensive to measure.