Northern California Twin Registry
If you and your twin are over the age of 18, live in the Bay Area, and are interested in registering, you will be invited to participate in studies and be eligible to receive payment for your participation.

The MIT Twins Study Homepage
A long-term study of language development in twins. The goal of the project is to compare language learning in identical and fraternal twins to determine which aspects of language and language learning have a heritable basis.

Research Projects - Twin Studies
The Department of Medical and Molecular Genetics at Indiana University dicusses the various twin studies they have empoyed.

The Center for Study of Multiple Birth
Recognized internationally as a unique resource for research and information about the causes, effects and problems of multifetal pregnancy.

Twin Research
Journal of the International Society for Twin Studies. Topics covered in the journal include behavioral genetics, complex diseases, endocrinology, fetal pathology and other areas of research.

Millennium Twins
A longitudinal sociological study of twins born in the new millennium.