The area is steeped in Quaker tradition. The Matinecock Friends meeting House at Piping Rock and Duck Pond Roads, now in Glen Cove but historically part of Locust Valley, was built in 1725. It was destroyed by fire in 1985 and rebuilt the next year. It is on the National Register of Historic Places. Two privately owned dwellings built around 1698 are now official town landmarks: the Joseph Weeks Jr. and William Hawxhurst houses on Oyster Bay Road. Two private schools in Locust Valley, Friends Academy and the Portledge School, each on more than 60 acres, have national reputations.
Today's one-square-mile, unincorporated hamlet of about 2,000 people is off the beaten path for most Long Islanders. Locust Valley has always had a wide identity; it is generally agreed that the surrounding incorporated villages of Lattingtown, Matinecock and Mill Neck, at least, are also a part of what is called Locust Valley. Several communities are under the postal and school umbrella of Locust Valley. Many neighborhoods, such as Brookville, Old Brookville and Upper Brookville, consider the Locust Valley town and shops as part of their own.