Block Island is part of Rhode Island and is located in the Atlantic Ocean approximately south of the coast of Rhode Island, and is separated from the mainland by Block Island Sound. The United States Census Bureau defines Block Island as Census Tract 415 of Washington County, Rhode Island. As of the 2000 census the population of 1,010 lived on a land area of . The island is a fragment of glacial terminal moraine (tracing through the Outer Lands region).

Block Island was named by the The Nature Conservancy as one of twelve sites in its list of "The Last Great Places" in the Western Hemisphere. Roughly 20% of the Island has been set aside for conservation.

The only town on the island is New Shoreham. The island is a popular summer tourist destination and is known for its excellent bicycling, hiking, sailing, fishing, and beaches. Two historic lighthouses are present on the island: Block Island North Light, on the northern tip of the island (established in 1829, current lighthouse was built in 1868), and Block Island Southeast Light, on the southeast side of the island (built in 1875). Much of the northwest tip of the island is an undeveloped natural area and resting stop for birds along the Atlantic Flyway.

Every summer the island hosts Block Island Race Week, a highly competitive, week-long sailboat racing event. On odd years, the event is held by the Storm Trysail Club, and on even years by the Block Island Race Week organization. Yachts compete in various classes, sailing courses in Block Island Sound, and circumnavigating the island.

Other popular events include the annual Fourth of July Parade and celebration. During these times the island's population can triple over the normal summer vacation crowd.