The WA Twin Register was established in 1997 and comprises all volunteering multiples - that is, twins, triplets, quadruplets and quintuplets - born in WA from 1980 onwards. Multiples who have already joined the Register have taken part in a number of research projects looking at asthma and allergies, behavioural problems, early language development and the impact of loss and grief on multiple birth families.

The WA Twin Register is the only population-based register of twins and other multiples in Australia, and one of a few twin-family registers anywhere in the world.

The research team is a partnership between public health and medical scientists in Western Australia, all of whom have an interest in the special needs of multiples. Two major research centres in WA - the Telethon Institute for Child Health Research (TICHR) and the Western Australian Institute for Medical Research (WAIMR) - are involved in running the Register. The Register has the support of the WA Branch of the Australian Multiple Birth Association and the Perth & Districts Multiple Birth Association, and is a node of the Australian Twins Registry.