Many of the buy-outs have led to a "cascade" of new investment from outside agencies which has led to communities becoming more self-sufficient and in some cases reversed decades of falling populations, the study says.
Community landowners now control 500,000 acres of Scotland, from Assynt in Sutherland to Gigha off the Kintyre peninsula. But the report's author warns the Scottish government and other funding bodies that some communities with few assets will need more help in the early stages of a takeover if they too are going to turn into success stories.
The study was carried out by Dr Rob McMorran, from the Perth-based Centre for Mountain Studies, part of the prospective University of the Highlands and Islands, who concludes that buyouts encouraged by the Scottish Parliament have had a positive impact on rural communities.
"There is a general feeling of security, stability and community confidence (after a buyout) and this can result in wider stakeholders showing a much greater willingness to become involved in the estate and invest in important services.
"Following buyouts communities also have a strong sense of ownership and empowerment. As a result of community members being involved, often in activities that they may not have done before you get a real build-up of knowledge and social capital in these communities. This facilitates communities to get to the point where they can look after themselves."
McMorran said the Knoydart Foundation, a community-led body that took over an estate in north-west Scotland for almost 800,000 in 1999 after a succession of private landlords, is now approaching self-sufficiency. He said without a buyout Knoydart was facing "community disintegration and continued decline" due to local insecurity, people leaving the area and lack of investment.
Since the takeover the population has increased, housing infrastructure has improved and a number of new businesses have started.
Lorne MacLeod, a director of Community Land Scotland, welcomed the study: "Ownership of land by communities allows so much to be done in terms of developing the assets. The process of going through a buyout is good in terms of gaining confidence in the community and improving the capacity for people to undertake projects. The effect of that exercise cannot be underplayed."