In 2004 the Kavli Institute for Theoretical Physics celebrated its 25th anniversary. Since its founding in 1979, the KITP has played a dynamical, some might even say crucial, role in the development of theoretical physics. Happily, the occasion of our 25th anniversary also coincided with the completion and dedication of our new wing.

We celebrated our anniversary and this past quarter century of theoretical physics by holding a special conference covering all aspects of theoretical physics, and consisting of a number of lectures and panel discussions. The conference opened with a review of all the exciting developments in theoretical physics in the last 25 years and closed with a special session in which the participants were asked to predict what exciting developments will occur in physics in the next 25 years (The 25 Questions).