In the early morning of January 11, 2000, while walking from home to his office at the J. Willard Gibbs Laboratory, Paul Sigler, one of the giants in structural biology of our time, collapsed and passed away. While 65 years old, an age when many may be resting on past successes, Paul was in mid-course, achieving greater and greater heights of structural and chemical understanding of basic biological systems of transcription, signal transduction, interfacial catalysis, and chaperonin-mediated protein folding. As a father of five grown children, he was also savoring, with his wife Jo, the arrival and maturation of eight grandchildren living in the United States, England, and Israel. We extend our deepest sympathies to his family.