Slighe Hiort is part of a Destination Development programme, which is to receive up to £8 million as part of the Islands Growth Deal, jointly funded by the UK and Scottish governments, along with local authorities.
Each of the centres will focus on aspects St Kilda’ heritage.
It is the UK’s only double World Heritage site and attracts global interest both for its natural features and also the human story of its people and culture, prior to evacuation in 1930.
Endorsing the memorandum of understanding (MoU), Joanna Peteranna, Western Isles manager of Highlands and Islands Enterprise (HIE), said: "This is a significant milestone and a real mark of commitment to delivering the three St Kilda projects with associated benefits for the whole of the Outer Hebrides. HIE looks forward to continuing to support the development of Slighe Hiort."
Donald Crichton, chairman of Comhairle nan Eilean Siar’s sustainable development committee, congratulated the groups for their perseverance over a number of years.
He said: “It is a real achievement to see community organisations in Uist, Harris and Lewis coming together over a shard interest in St Kilda, its heritage and culture. “
Ionad Hiort – the St Kilda Centre – will be built on a clifftop location in the Uig area of Lewis, replicating as far as possible the features of St Kilda in an accessible location.
It will be principally a Gaelic Centre, reflecting the language of St Kilda, and will provide extensive digital and archival interpretation of the islands.
Iain Buchanan, chairman of Ionad Hiort, said: “Although we’ve had our MoU in draft format for a number of years, it is always reassuring to see signatures on such documents and I very much hope the Hiort groups can work collaboratively for many years to come."
Sealladh Hiort - the St Kilda Viewpoint Centre in North Uist - has the best direct views of the archipelago on clear days.
Whilst keeping St Kilda as its core theme, other displays and interpretations will differentiate this from the other projects by also focusing on outlying Hebridean islands which have had similar cultural and natural histories to St Kilda and also its modern role in defence and maritime matters.
Alasdair MacEachen, chairman of Sealladh Hiort said: “We are delighted to reach this stage and to sign off our agreed collaboration with both Lewis and Harris projects, as we jointly move forward with our plans to promote the various aspects of the story of St Kilda, the place and its people.”
The Harris project – Seallam Hiort na Hearadh – will be based at an upgraded genealogical centre in Northton.
Bill Lawson, who founded Seallam with his late wife, said: “My main interest now is in preserving that for the future.”
Hiort na Hearadh will use digital technology to create interactive experiences enabling understanding of who the people of St Kilda were, how they lived and what became of them..
The MoU commits the three projects to “raise the profile of St Kilda and its cultural and natural history, through co-ordination of the activities of its member groups for the benefit of the whole Western Isles”.