Monadnock State Park in Jaffrey, New Hampshire, United States, is a 1,017-acre state park located on and around 3,165-foot Mount Monadnock. The park is surrounded by thousands of acres of protected highlands.
The park is open to hiking, picnicking, camping, backpacking, snowshoeing and cross country skiing. Backcountry skiing is possible on some of the lower trails. There are two campgrounds.
A per-person fee is charged to park at the Old Toll Road and State Park Headquarters trailheads. There are no roads to the summit, and the Old Toll Road, which leads to the Halfway House site, is closed to vehicles.
In 1987, Mount Monadnock was designated a National Natural Landmark.