The Cornell Lab of Ornithology is an international center for the study, appreciation, and conservation of birds located on a 200-acre wildlife sanctuary in Ithaca, New York. Founded in 1915 by Arthur A. Allen, the world’s first professor of ornithology, the Lab originally became known for its pioneering work in bird photography and has been involved in public education ever since. In fact, Dr. Allen’s desire to embrace the public by involving bird watchers in field research launched the Lab on an important path that it continues to this day—that of breaking down barriers between “science” and “public” by actively engaging citizens in the process of scientific inquiry. This chapter will focus on the development and impact of three Citizen Science Lab projects: Project Feeder Watch, the Great Backyard Bird Count, and eBird.