Edward C. Carter II began this project to create a souvenir for the American Philosophical Soc. (APS) 250th Anniversary Celebration in 1993. The APS is the oldest learned society in the U.S. and one of the most prestigious organizations of its kind in the world. The story of the APS and those men and women members who have helped promote useful knowledge throughout the years is an extraordinary story. The general observations on these achievements here are intended to serve as an introduction to this account of the APS. Now midway through its third century, its form and flavor remarkably little changed, the APS is engaged in promoting useful knowledge, as it has always been. Illustrations.