Chepstow is an Italianate-style house on Narragansett Avenue in Newport, Rhode Island. Built in 1860 for Edmund Henry Schermerhorn, cousin to Caroline Webster Schermerhorn Astor, the house was designed by notable Newport architect George Champlin Mason and built by Cyrus H. Peckham. Beginning in 1860 with the construction of the Schermerhorn and Edward Ogden houses, Mason transformed the Narragansett Avenue neighborhood into one of Newport's earliest cottage colonies, featuring Chepstow and its neighbors, Gravel Court and Starboard House. Like other Mason houses built in the Italianate style, including the now-demolished By-The-Sea, Chepstow's design includes a French or Mansard roof and a distinctive single-story bay window to one side of the front entrance. Despite a series of additions, Chepstow retains many of its original design features, including smooth exterior boarding, first-floor arched windows, and bracketed trim.

Although the house was originally constructed as a summer cottage, Edmund Schermerhorn "for six or seven years... had lived the life of a recluse" ("Death of a Rich Recluse", The New York Times, October 2, 1891) as a year-round resident. Schermerhorn never married and had no children, and upon his death in 1891, the house was willed to his brother, William Colford Schermerhorn. William Schermerhorn utilized the property as a summer residence alongside his family. Upon his death, William Schermerhorn willed all of his real estate to his wife, Ann E.H. Cottenet Schermerhorn, who in turn willed shares of the property to their three daughters. Following the deaths of Ann Schermerhorn and her daughter, Sarah, the property was sold to R. Horace Gallatin in 1911 for an undisclosed price. Ownership was transferred to Gallatin's wife, Emily Lorillard Morris Gallatin, in 1913. Over the following years, Emily Morris Gallatin purchased adjoining parcels of land to expand the property to its current extent, and named the estate "Chepstow" in honor of a town and castle in Wales with significance to the Morris family history. R. Horace Gallatin, predeceased by his wife, enacted Emily's wishes for the property in his will, leaving the house in equal shares to Emily's cousin, Lewis Gouverneur Morris, and his two daughters, Alletta and Betty. In 1949, Alletta Morris, then married to Byrnes MacDonald, purchased her father's and sister's shares of the property to become its sole owner.

Alletta Morris (MacDonald) McBean utilized the estate as a summer residence from 1949 until her death in 1986. In the 1970s, she oversaw the addition of a "Garden Room" at the rear of the building, and applied her skill and passion for découpage to many surfaces throughout the home. Alletta was a noted hostess among Newport summer residents; her Chepstow table settings were featured in the August 1982 issue of Town and Country magazine, and, along with her second husband, Peter McBean, she hosted an annual banquet dinner at Chepstow during the weekend of the Newport Country Club golf tournament. Among many other philanthropic ventures, Alletta was a Trustee of The Preservation Society of Newport County , and was posthumously awarded the Society's Antiquarian Medal in 1986. Alletta gifted Chepstow to the Preservation Society in her will, with the provisions that her husband, Peter McBean, would retain the right to use the property as his summer residence until his death, and that the house would be preserved as a historic house museum. In 1998, following the 1997 death of Peter McBean, the house opened to the public as a museum, and continues to open for tours throughout the summer.