Millennium Twins
A longitudinal sociological study of twins born in the new millennium.
http://www.millennium-twins.de
Sleep Research Study for Twins
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.
http://www.uphs.upenn.edu/sleepctr/clinicalresearch/twins.pdf
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.
http://www.multiplebirth.com/
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.
http://www.australianacademicpress.com.au/Publications/Journals/Twin_R/TResearch.htm
Twin Studies
From the Institute of Behavioral Genetics at the University of Colorado. A handful of studies for twins of all ages.
http://ibgwww.colorado.edu/~agross/ibg/twinsites.htm
Twin Studies of Homosexuality
An unpublished dissertation on twins and studies in homosexuality.
http://www.dai.ed.ac.uk/homes/timt/papers/twin_studies/
Twins Personality Survey
A twin survey on personality, conducted by researchers at Virginia Commonwealth University.
http://www.outofservice.com/twins/