The IGRS is a UK-registered charity, based in London, and was the earliest society founded to promote the pursuit of Irish genealogical research.

The IGRS library is the largest and most important private collection of Irish genealogical material outside of Ireland.

Acquisitions of genealogical material were first stored at Gray's Inn, London, before being transferred to Thornton College, Bletchley, Buckinghamshire, during World War II.

Membership is open to all applicants who have an interest in Irish ancestry and it has typically ranged between 500 and 1100 over recent decades.

Fourteen volumes have been published, with the 15th currently being issued to the membership in the usual six parts.