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.

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.

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

Located at St Thomas' Hospital, London, UK.

Newsletter, research information, survey.

Events, journal, bylaws, membership information.

Includes a newsletter, registry for twins, study information and conferences.

From the Institute of Behavioral Genetics at the University of Colorado. A handful of studies for twins of all ages.

An unpublished dissertation on twins and studies in homosexuality.

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.

A twin survey on personality, conducted by researchers at Virginia Commonwealth University.

The University of Pennsylvania is recruiting same-sex twins living in the eastern time zone who are between the ages of 25 and 59 to participate in a sleep research study.