This multi-institutional National Science Foundation Friction Stir Processing Industry/University Cooperative Research Center (I/UCRC) was started in October 2004. Four leading programs on Friction Stir Welding and Processing at the South Dakota School of Mines and Technology (SDSM&T), Brigham Young University (BYU), the University of South Carolina (USC), the Missouri University of Science and Technology (MST) , and the Wichita State University (WSU) formed a partnership for this center. BYU is the lead institution for the Center. Friction Stir Welding (FSW) is a revolutionary solid-state (below solidus) joining technology patented by The Welding Institute (TWI-UK) in 1991. It has seen an explosive growth in research, development, and application over the last decade. FSW has shown higher strengths, fewer defects, lower residual stress, and less distortion in single pass, full penetration, thick section (>1 inch) aluminum applications. FSW of metal matrix composite, titanium, and ferrous alloys still require fundamental research to maximize this technology. Friction Stir Processing (a variant of FSW) has received increased interest as a rivet replacement technology and a microstructural modification technique to induce superplasticity in thick section materials, to locally modify the microstructure in complex castings and to add micron and submicron particles into metal surfaces.