The American Prairie Foundation is a nonprofit organization located in the U.S. state of Montana. The foundation's objective is to build one of the largest^[6] wildlife reserves in the continental United States through a combination of new land acquisition and public land integration into the project, called the American Prairie.^[7] To accomplish this, the foundation estimates that it must acquire 500,000 acres (2,000 km²) privately, which would then link together over 3,000,000 acres (12,000 km²) of existing public property. The Charles M. Russell National Wildlife Refuge is one of the project's anchor properties.

The American Prairie Foundation (doing business as American Prairie) seeks to create a landscape reminiscent of that seen by the Lewis and Clark Expedition.^[8] The American Prairie Foundation developed a 7-point scale to evaluate land based on ten ecological conditions including plant diversity, grazing, fire, hydrology and predators to measure the impact of reserve management activities.^[9]

Approximately ten percent of the funding comes from private foundations supporting land conservation and the remaining ninety percent comes from individuals living in 46 states and eight countries. Approximately 20% of its donors reside in the state of Montana.^[10] As of December 2013, they had raised $67.3 million in cash and pledges since 2002.^[11]