Cook Forest State Park is a 8500-acre (34 km2) Pennsylvania state park in Clarion County, Pennsylvania, in the United States. The park is the third largest in the state forest system after Susquehannock State Forest and Tioga State Forest. Cook Forest State Park is known for its old growth forests and the Clarion River, which flows through the park.
The park was established in 1925 and named after George Washington Cook, a lumberman and conservationist who donated 400 acres (160 ha) of land to the state for the park. The park is home to a variety of plant and animal life, including black cherry, red maple, eastern hemlock, white pine, and deer, bear, and turkey. The park also has a number of hiking trails, picnic areas, and campgrounds.