In 2007 we celebrate 25 years of CHI conferences. What better way to commemorate this milestone than with a retrospective of photos celebrating the people, activities, and events of CHI over the decades? Ben Shneiderman, one of the founders of the CHI Conference, has been a diligent photographic chronicler of the annual event. He helped prepare a photo spread in the following pages that seeks to reflect the conference’s development over the years. We asked Ben to offer brief comments about his experiences as the unofficial photographer of CHI, specifically as regards both the art and science of his memorable work.