The origins of the preserve date to 1869, when twin brothers Albert and Alfred Smiley purchased Lake Mohonk and established the Mohonk Mountain House. On February 26, 1963, the Smiley family, friends, neighbors and supporters formed the Mohonk Trust to protect the area's unique natural landscape for future generations. The "property" of the Mohonk Trust on that day in 1963 consisted of $100, a gift from Mabel Craven Smiley. Land was acquired by the Mohonk Trust over the years, and it became the Mohonk Preserve Inc. in 1978. According to their 2017 IRS Form 990 their assets then exceeded $25 million. Through the support of members, donors and partners, the preserve has become a center for outdoor education and a conservation advocate, especially for natural lands in the Shawangunks and the Hudson Valley. Its mission includes land protection and stewardship, sponsorship of environmental education programs, which according to Preserve officials have served more than 100,000 children over a thirty-year period, and maintenance of biological, weather, and natural history records spanning more than a century.