Gladwyne is an affluent suburban community in Montgomery County, Pennsylvania, United States along the historic Philadelphia Main Line. The population was 4,050 at the 2000 census.
Like the rest of the region, Gladwyne, known until 1891 as "Merion Square", originally was settled by Welsh Quakers beginning in 1682. It was given its new name to lessen confusion with the many "Merions" in the area, including the town of Merion, Lower Merion Township, and Upper Merion Township, and in imitation of the Welsh names of adjoining towns, although its new name was meaningless in Welsh. Twenty-four mills operated along Mill Creek through the beginning of the twentieth century, and the major road through residential Gladwyne runs along the banks of the creek. After the American Civil War and following construction of the Pennsylvania Railroad's Main Line west from Center City, wealthy Philadelphians located many of their summer homes there.The development of the Schuylkill Expressway (I-76) in the 1960s and the subsequent development of King of Prussia as a major business center increased Gladwyne's appeal, as it was the Main Line town situated closest to the Expressway and midway between King of Prussia and Center City Philadelphia. The Gladwyne Elementary School was built in 1958 to accommodate the children of these new residents and the Gladwyne Free Library (part of the Lower Merion Library System) was renovated and expanded as well. Yet the core of the village, built originally at the convergence of Youngsford and Righter's Mill Roads during the latter part of the eighteenth century, remained essentially the same, allowing Gladwyne to retain all of its original historic character and at the same time enjoy the conveniences of modern suburban living, such as a centrally located supermarket with ample parking, pharmacy, tavern, and restaurants.The Gladwyne Historic District was added to the National Register of Historic Places in 1980.