The Swift River Reservation is a 439-acre (178 ha) open space preserve located in Petersham, Massachusetts, United States.

The property, named after the East Branch of the Swift River (a tributary of the Ware River), is managed by the land conservation non-profit organization The Trustees of Reservations and offers 7 miles (11 km) of trails available for hiking, horseback riding, mountain biking, and cross country skiing.

[1] Ledges, river corridor, woodlands, scenic vistas, and wetlands characterize the preserve.

The East Branch of the Swift River passes through the Slab City and Nichewaug tracts.

The Swift River Reservation is part of a larger area of protected open space including the Trustees of Reservations' Brooks Woodland Preserve, Harvard University's Harvard Forest, and state owned land.