- TwinStuff.com
- Bulletin boards, twin games, photo gallery, information for parents, TV and movie twins, twin events, and information. - Twinsworld - Offerings include a twin casting agency, twin events, reunion of twins placed for adoption or separated at birth, message boards, links, photos, contests, and research.
- Facts About Multiples - Information on twins, triplets, quadruplets, quintuplets and higher order multiples. Features a database of multiple birth families, statistics, basic information on twinning, world records and information on fakers.
- Twin Connections - Twin Connections celebrates the unique and mysterious bond between twins by providing a place for twins, and their families and friends, to share and read twin stories and photos, learn interesting twin facts and news and join an online twin community.
- The International Twins Association - A non-profit, family-oriented organization to promote the spiritual, intellectual, and social welfare of twins and multiples throughout the world.
- BellaOnline Twins - Information on vanishing twins, events, scholarships and twins in school.
- TwinsRealm.com - Mirror twins from Australia share photos, twin stories, links and information on twin festivals and celebrations.
- Incredible Births - Site designed with emphasis on multiple births, such as twins, triplets, quadruplets, quintuplets.
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- Pregnancy@ (15)