Callahan State Park is a public recreation area covering 958 acres (388 ha) mostly in Framingham and Marlborough, Massachusetts, with a small section in the adjoining town of Southborough.

[5] It was officially named in honor of local newspaperman Raymond J. Callahan by an act of the Massachusetts legislature in 1971.

[6] The park is home to a wide variety of trees both coniferous and deciduous.

Wildlife include snapping turtles, spotted turtles, red bellied turtles, white tail deer, water snakes, tree frogs, most New England frog and toad varieties, minks, fisher cat, red fox, coyote, largemouth bass at Eagle Pond, various common trout, sunfish and blue gills, herons, egrets, bobolinks, goldfinches, orioles, red tail hawks, mocking birds, sparrows, swifts, swallows, grackles, cow birds, cat birds, barred owl, other various birds of prey, robins, cardinals, and blue jays.

The park has 7 miles (11 km) of trails for hiking, mountain biking, cross-country skiing, and horseback riding.