In 1676 Joshua, son of Uncas and Sachem of the Mohegans, bequeathed his hunting grounds in the heart of eastern Connecticut to sixteen men of Norwich. This historic tract comprised the present towns of Windham, Mansfield, Chaplin, Scotland, and part of Hampton. Joshua's Trust, however, has extended its interest to Ashford, Columbia, Coventry, Lebanon and Willington, so that all ten towns of the Windham Region are included.

After three hundred years as a land of forest, farms, and villages, this ancient tract has been caught up in the pervasive urbanization of our time. There are now more than 75,000 people living in the Windham region. However, the countryside need not be destroyed by development pressure. Instead, development can be guided and directed so that open space is preserved by conservation easements and/or restrictions even as the needs of people are met. Joshua's Land Trust is one vehicle by which this dual goal can be furthered.

Joshua's Tract Conservation and Historic Trust was organized and incorporated in 1966. It had grown out of the joint initiative of the Mansfield Historical Society and the Mansfield Conservation Commission. Interested persons from the surrounding area joined the effort. The Trust's initial financial assets totaled $1400 obtained from 56 founding contributors. The Trust acquired its first property, Bradley-Buchanan Woods, in 1970. Six more properties were secured during the 70s including the historic Gurleyville Gristmill and miller's cottage, birthplace of Wilbur Cross who became one of Connecticut's Governors. The pace of acquisitions accelerated greatly during the 80s when 18 tracts were added to the Trust's holdings and this acceleration continued through the 90s. The Trust has also been actively working with landowners in establishing conservation restrictions (easements).

In 2009 Joshua's Land Trust protects over 4,000 acres of conservation lands in Connecticut, found in the towns of Andover, Ashford, Chaplin, Columbia, Coventry, Franklin, Hampton, Mansfield, Lebanon, Storrs, Tolland, Willington, and Woodstock. Trust membership continues to grow. In 1992 the Trust obtained from the Town of Mansfield a 30-year lease on the Eagleville Schoolhouse and renovated it for use as an office and headquarters.

The Trust's logo is the mark made by the original Joshua. It is commonly referred to as "the critter".