Environmentalists have launched a legal challenge to housing developments planned for sites in the Cairngorms National Park.
The Cairngorms Campaign opposes plans for a new community at An Camas Mor, near Aviemore, and schemes proposed for Grantown-on-Spey and Kingussie.
Three conservation groups have jointly appealed to the Court of Session.
The park authority (CNPA) said it had received details of the challenge and was considering its response.
An Camas Mor was approved by the authority in June last year.
Rothiemurchus Estate's project would see 1,500 homes and business and community facilities built in phases, close to Coylumbridge.
The CNPA said it would be one of the "biggest developments in a generation".
The Cairngorms Campaign, which is based in Aberdeenshire, along with the Scottish Campaign for National Parks and Badenoch and Strathspey Conservation Group have jointly lodged the appeal.
The action concerns the CNPA's local plan, a document which guides development in the park.
Spokesman Bill McDermott said: "The park authority has been acting as the developers' friend. It should be a conservation agency not a development agency."
He added: "We're fully aware of the need to house local people, and have well-balanced communities with homes for young people who couldn't otherwise afford to live in the park.
"But the authority will trash the park the way they're going. Theirs is a recipe for masses of holiday homes, and social incohesion."
The CNPA said it had received details of the appeal on Tuesday morning.
A spokeswoman added: "It is quite a lengthy and complex document and we will need time to read it and consider our response to the various arguments it sets out."