This volume was prepared in conjunction with a Symposium held in Berkeley June 5–7, 2005, as a tribute to Professor Pravin Varaiya. The contributions represent most of the lectures given at the meeting. The Symposium brought together former students, collaborators and friends from throughout the world to celebrate Pravin’s career as he approached the memorable occasion of his 65th birthday. The authors, speakers, organizers, supporters and attendees of the Symposium are very pleased to dedicate this work to Pravin, to congratulate him on his many seminal contributions, and to thank him for his leadership in the ?elds of systems, control and networks over the past four decades. Pravin Varaiya was born on October 29, 1940 in Bombay, India. He earned the B. E. degree in Electrical Engineering from the University of Bombay in 1960, and then began his graduate studies at the University of California, Berkeley. The early 1960swasanexcitingtimeduringwhichthefoundationsofsystemsandcontrolwere developed, and Berkeley contributed to this development through the research of Professors Arthur Bergen, Charles Desoer, Mac Hopkin, Eli Jury, Elijah Polak, Otto Smith, and Lot? Zadeh. Professor Eugene Wong joined the faculty in 1963 and c- tributed to the understanding of stochastic systems. Berkeley attracted outstanding visiting faculty, including Moshe Zakai and Bill Root. The faculty trained and m- tored a strong group of graduate students, including Mike Athans, Dick Mortensen, Jack Wing, Jim Eaton, Cesare Galtieri, Barry Whalen, and Pravin Varaiya.