ABC Club
   The largest German organisation for families with higher multiple birth children, from triplets onwards.
   http://www.abc-club.de/

National Organization of Mothers of Twins Clubs, Inc.
   Official site; a non-profit, nation-wide support group for parents of twins and higher order multiple birth children.
   http://www.nomotc.org/

The Association of Finnish Triplet Families
   Mostly in Finnish, but has an English section and lots of international links.
   http://www.kolumbus.fi/suomen.kolmosperheet/

Twins Plus Singapore
   Support group for parents of twins and other multiples in Singapore.
   http://www.twinsplussing.com/