Organized October 8, 1886, continuing the Chicago Stamp Collectors Union, which was organized December, 1884. The CPS is APS Chapter No.1, and one of the two organizations with the longest uninterrupted service to philately in the United States.

Each year in November the Chicago Philatelic Society hosts CHICAGOPEX — one of the four largest stamp shows in the country — that attracts dealers, exhibitors and stamp enthusiasts from around the nation and the world.