Martha's Vineyard, often simply called the Vineyard, is an island in the U.S. state of Massachusetts, lying just south of Cape Cod. It is known for being a popular, affluent summer colony, and includes the smaller peninsula Chappaquiddick Island. It is the 58th largest island in the U.S., with a land area of about 96 square miles (250 km), and the third-largest on the East Coast, after Long Island and Mount Desert Island. Martha's Vineyard constitutes the bulk of Dukes County, Massachusetts, which also includes the Elizabeth Islands and the island of Nomans Land.
The island's year-round population has considerably increased since the 1960s. In the 2023 Martha's Vineyard Commission report, the year-round population was 20,530, an increase from 16,460 in 2010. The summer population swells to more than 200,000 people. About 56 percent of the Vineyard's 14,621 homes are seasonally occupied.