Alta Rockefeller Prentice (April 12, 1871 — June 21, 1962) was an American philanthropist and socialite. She was the third daughter of philanthropists John Davison Rockefeller (1839—1937) and Laura Celestia "Cettie" Spelman (1839—1915). Alta married attorney Ezra Parmalee Prentice (July 29, 1863 — 1955), son of Sartell Prentice and Jemima Parmalee, in 1901. Alta and Ezra had three children: John Rockefeller Prentice (1902—1972), Mary Adeline Prentice (1907—1981), and Spelman Prentice (1911—2000).
In 1910, Alta and Ezra bought 1,400 acres (5.7 km²) of land near Williamstown, Massachusetts. Elm Tree House, the Prentices' 72-room summer home on Mount Hope Farm, was completed in 1928. In the 1930s and 1940s, several geneticists were employed by Ezra to develop more profitable farm animals, particularly cattle and poultry. At that time, Mount Hope Farm was one of the most outstanding experimental farms in the United States.