Organizations

Chicago Playing Card Collectors, Inc.
Club devoted to sharing the knowledge and enjoyment of collecting playing cards of all kinds.
http://www.cpccinc.org/

English Playing Card Society
Organization in the service of collectors of playing cards, card games and related ephemera.
http://www.wopc.co.uk/epcs/index.html

52 Plus Joker
The American Antique Deck Collectors Club is for those interested in antique playing card decks and for collectors playing card decks of all sorts.
http://www.52plusjoker.org/