Rhododendron State Park is a public recreation area and nature preserve occupying 2,723 acres (1,102 ha) on and around Little Monadnock Mountain in Fitzwilliam, New Hampshire, United States. The state park contains a 16-acre (6.5 ha) stand of native Rhododendron maximum, the largest of nineteen similar stands in central and northern New England, the northern limit of their growing range. The stand was designated a National Natural Landmark in 1982. The park also includes wild blueberries, cranberries, mountain laurel, heathers, mayflower, and wintergreen.

Fitzwilliam is a town in Cheshire County, New Hampshire, United States. The population was 2,351 at the 2020 census. Fitzwilliam is home to Rhododendron State Park, a 16-acre (6.5 ha) grove of native rhododendrons that bloom in mid-July.