Starting in 2006, users requesting high-performance computing resources from the National Science Foundation will have seamless access to all computational resources at the San Diego Supercomputer Center (SDSC) and the National Center for Supercomputing Applications (NCSA) within the TeraGrid environment. TeraGrid will provide the national user community access to the Tungsten, Radium and Copper systems at NCSA and SDSC's DataStar and Blue Gene systems in addition to TeraGrid systems in Texas, Indiana, Tennessee and Illinois. Access to the SDSC and NCSA systems will bring the TeraGrid's total computational performance to a peak of about 110 trillion calculations per second. The move represents a large scale integration effort by NCSA and SDSC, as well as the TeraGrid partners, to provide a large-scale national grid-enabled computational and data management facility. NCSA and SDSC are founding partners of the TeraGrid program and have deployed large IA-64 clusters and other resources within the TeraGrid since its inception. Integrating new hardware into TeraGrid carries with it a large-scale software challenge - integrating the software systems of the new hardware as well as extending security, accounting, scheduling and other systems. "We are proud to provide SDSC's computational and data resources to the national science and engineering community through TeraGrid," said Dr. Francine Berman, SDSC Director. "TeraGrid is a true pioneer in national-scale grid efforts, and provides a platform for new discovery for the research community. SDSC's high performance computers, national reference data collections and archival storage and outstanding staff are an important part of TeraGrid's resources, and we are committed to working with the TeraGrid partnership to provide the very best resources for the national user community." "NCSA and SDSC are demonstrating the power of the TeraGrid program as an extensible partnership to provide the scientific community with unparalleled access to computational resources to address their needs in ways that have previously never been possible," said Charlie Catlett, Director of TeraGrid. He adds that, "the collaborative efforts among the TeraGrid partners have been critical to providing scientists with access to all of the TeraGrid resources at NCSA and SDSC." "This transition enables scientists and engineers to more easily tap the resources they need and makes the TeraGrid a truly seamless cyberinfrastructure for the national research community," says NCSA Director Thom Dunning. One benefit of the move is that TeraGrid users with "roaming" allocations will now have access to all NSF-supported systems at NCSA and SDSC, as well as the TeraGrid systems at other Resource Provider sites around the country. Users can use a roaming allocation to run on the systems at opportune times, explore their code's performance on new architectures, or expand their science via grid workflows. SDSC and NCSA are two of eight supercomputing centers across the nation that together provide the TeraGrid's computational, storage, software, and instrument and visualization resources, along with user support and related services. The other partner sites, also called Resource Providers (RPs), are: The University of Chicago/Argonne National Laboratory; Indiana University; Oak Ridge National Laboratory; Pittsburgh Supercomputing Center; and Purdue University.