Radio Society of Great Britain
Links to IARU ARDF Sites

Full Rules
http://www.ardf-r1.org/files/Rules_V2.8_A_(2009).pdf Rules for setting up large International Events. (As at Aug 2006, link from Region 1 website not working)
http://www.ardf-r1.org/files/Rules_V2.10B_2012.pdf Rules for Competitions.

Sites of various national societies
Germany http://www.darc.de/referate/ardf/english.htm Note: the German language version is frequently more up to date.
France click here
Belgium http://www.uba.be/en/ardf/competition-calendar
The Netherlands http://ardf.veron.nl
Canada http://www.rac.ca/opsinfo/ardf.htm
Slovenia http://lea.hamradio.si/arg
Czech Republic http://www.ardf.cz
Norway http://www.ardf.no/New/Default.asp# The English language version is not always updated.
Denmark http://www.qsl.net/oz7fox
USA http://www.homingin.com

IARU Region 1 ARDF Working Group
http://www.ardf-r1.org

Other interesting sites
http://en.wikipedia.org/wiki/Amateur_Radio_Direction_Finding An on-line encyclopedia gives an excellent description of ARDF including good coverage of the history and origins of the sport.
http://www.qsl.net/on7yd/ardf.htm The site of Rik Strobbe (the Mr DF of Belgium). It includes lots of good technical stuff regarding suitable transmitters and controllers
http://www.df7xu.de Site of Dieter Schwider in German. Good list of German events.
http://home.introweb.nl/~pa3fdc/ Site of Ferry de Vroom in English and Flemish. Lists Dutch and Belgian events.
http://www.foxhunt.com.au Site of Bryan Ackerly VK3YNG (Australia). Packed with details of kits and innovative ideas for ARDF equipment.