Grantham is an unincorporated community in Upper Allen Township, Cumberland County, in the U.S. state of Pennsylvania, best known today for the Christian liberal arts college, Messiah University, whose students make up most of its population.

It was destroyed by fire prior to 1957 and stood derelict for many years; eventually it was demolished to provide a new maintenance facility for the growing college.

The other early business was the mill, a large stone building built in 1775, located on a chase that feeds from Yellow Breeches Creek.

At the far edges of the community are some newer townhomes, and since the closing in 2004 of Grantham Road at U.S. Route 15 (a long-time dangerous intersection) the town enjoys relative peace and quiet.

Summer weekend evenings are often punctuated by the roar of nearby Williams Grove Speedway, but traffic through town is now minimal, which allows for safe biking and walking along Grantham's roads.