The High Energy Astrophysics Science Archive Research Center, the HEASARC, is a site in the Astrophysics Data System (ADS) that supports multi-mission X-ray and gamma-ray archival research. It is a collaboration between the LHEA and the NSSDC, with the HEASARC director being a member of the LHEA. The HEASARC will contain archival data from the current and upcoming missions BBXRT, ROSAT, GRO, Astro-D and XTE. This includes the raw data, the derived data products, catalogs of results, the calibrations, the analysis software and the documentation, as well as providing the necessary scientific expertise and support. The HEASARC also archives and distributes the data from earlier X-ray and gamma-ray missions. The National Space Science Data Center (NSSDC), colocated at GSFC, will support the required data archiving and retrieval, as embodied in its overall role as NASA's long-term data archive. The HEASARC will provide the scientific interface required by the community to obtain meaningful results from the data.