ICRISAT maintains a substantial Arachis germplasm collection of 14,723 accessions, comprising 14,310 accessions of cultivated peanut (Arachis hypogaea L.) from 92 countries and 413 accessions of wild species representing 43 taxa. All germplasm is freely available for distribution. Forty-five percent of the cultivated peanut collection is of var. hypogaea, followed by 35.7% var. vulgaris and 16.1% var.fastigiata. Varieties hirsuta and aequatoriana are represented by 20 and 15 accessions, respectively. All passport and characterization data are accessible through the internet. To enhance the utilization of the collection and understand the diversity it contains, efforts have focused on characterization and documentation of the collection and the formation of a core of 1704 A. hypogaea accessions. These are representative of the genetic diversity in the entire collection. The core provides an entry point into the collection and is currently being evaluated for maturity, biotic, and abiotic stress resistance and quality parameters, including aflatoxin contamination. A subset of the core is used in prescreening for polymorphic molecular markers. Evaluation of the wild Arachis collection to major abiotic stresses is a continuing process. Future efforts in both the wild and cultivated collections will focus on germplasm exchange and acquisition, and specific regions for future collections are identified. The development of molecular markers for diversity assessments in all Arachis taxa and alternative strategies for utilization of the wild species are also important areas of research.