William Hale Winsborough died unexpectedly on Thursday, August 18, 2011, in San Antonio. He was born on July 24, 1960, in Chicago, IL, and was 51 years old at his death. Will Winsborough received his bachelor's, master's, and doctoral degrees from the University of Wisconsin. His Ph.D. in computer science, with a minor in mathematics, was granted in 1989 for his dissertation on "Automatic, Transparent Parallelization of Logic Programs at Compile Time." Over his career, Will Winsborough held several positions in both industry and academia. At the time of his death, he was a professor of computer science at the University of Texas at San Antonio, where he had been on the faculty since 2005. He was previously affiliated with George Mason University in Fairfax, Virginia; Network Associates in Rockville, Maryland; Transarc in Pittsburgh, Pennsylvania; Pennsylvania State University, State College, Pennsylvania; the University of Chicago and Argonne National Laboratory in Chicago, Illinois; and the University of Wisconsin in Madison. Professor Winsborough was a well-known researcher who worked in programming languages until the late 1990's when he started working in computer and information security and privacy. He was a well-connected member of the information security community who served on numerous organizing and program committees including ACM CCS and IFIPTM. He maintained many active collaborations with researchers throughout the world. He considered himself a theoretician and was most broadly known for his research on trust management and trust negotiation. His research in this area focused on developing access-control techniques that enable users and resource providers to establish appropriate trust relationships automatically, without prior contact. Working with colleagues at Stanford and Purdue, he designed a family of efficient, expressive policy languages called Role-based Trust-management (RT), which supports a rich model of delegation, and provides a natural, highly scalable administrative model. His research earned him a DARPA Award for Excellence in Industrial Research in 2003, and his work on Trust Negotiation was recognized as a runner up for the PET Award for Outstanding Research in Privacy Enhancing Technologies in 2007. Most recently, Professor Winsborough was leading a project at the University of Texas at San Antonio to create a framework in which software systems, such as those processing electronic medical records, can be developed and shown to comply with formal rules about how private information can be disseminated. Professor Winsborough was especially enthusiastic about this project, because it allowed him the opportunity to return to combine his earlier love of programming languages with security in the development of a History-Aware Programming Language. Professor Winsborough will be affectionately remembered as a mentor for his junior colleagues and students. He would often spend long hours in his office working with them, thinking through problems, and eventually crystallizing solutions into elegant formalisms. He was deeply concerned for the well-being of the students under his care. On the evening before his death, he presided over a meeting of department faculty seeking to improve the department's curriculum with respect to computer science theory. Will will also be remembered for his love of cooking and photography as well as playing with his dog. He relished inviting students, colleagues, and friends to join his family for elaborate holiday dinners. He was also an enthusiastic amateur photographer who could often be seen taking pictures at department picnics. He is survived by his wife, Maria de Fatima Winsborough; his parents, Halliman H. and Shirley H. Winsborough of Madison, WI; and his brother, Edward H. Winsborough of Edina, MN.