PWSAI was started by parents in the late 1980s as a support group for people with PWS and their families in Ireland. It formalised its status in 2002 when it became a company limited by guarantee. It has retained company status since and in 2012 changed its memorandum and articles of association to allow it to begin formally registering members. PWSAI has a full-time Development Officer whose role is fully funded and it also relies on volunteers for other  activities. It is audited annually and submits annual accounts to the Companies Office.