Edward C. Carter II began this project to create a souvenir for the Am. Philosophical Soc. (APS) 250th Anniversary Celebration in 1993 by expanding the 7-page “Brief History” which occationally appears in the APS “Year Book.” But when he began to review published sources on the history of the APS, he realized that he had to do much more. The APS is the oldest learned soc. in the U.S. & one of the most prestigious orgs. of its kind in the world. The story of the APS & those men & 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 mid-way through its third century, its form & flavor remarkably little changed, the APS is engaged in promoting useful knowledge, as it has always been. Illus.