Stony Brook is a hamlet and census-designated place (CDP) in the Town of Brookhaven in Suffolk County, New York, on the North Shore of Long Island. Begun in the colonial era as an agricultural enclave, the hamlet experienced growth first as a resort town and then to its current state as one of Long Island's major tourist towns and centers of education.The population was 13,740 at the 2010 census.
Stony Brook began as a satellite community of adjacent Setauket, New York, the Town of Brookhaven's first settlement. Stony Brook was a remote area during the 18th century aside for a modest amount of commerce near the mill at the intersection of Main Street and Harbor Road.The current mill, which replaced the 1699 original, was built in 1751 and ground grain into the 1940s until being repurposed for public tours. For religious services and education, the hamlet's original residents had to attend institutions in the neighboring communities of Setauket and St. James. In the latter half of the 18th century, activity began to shift from the mill area north toward the Harbor as new residences, a number of which still stand, were constructed.The community's development was stalled by its poorly accessible harbor relative to nearby Setauket and Port Jefferson. In the 1840s, the local painter William Sidney Mount led a call for the harbor's dredging. This was completed twice, but after the harbor filled in both times the effort was abandoned. Lacking the resources of its neighboring harbor settlements, Stony Brook based its economy on agriculture and the cordwood industry.