Block Island is part of the U.S. state of Rhode Island. It is located in the Atlantic Ocean about 13 miles (21 km) south of the coast of Rhode Island, 14 miles (23 km) east of Montauk Point on Long Island, and is separated from the Rhode Island 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 2010 census the population of 1,051 lived on a land area of 9.734 square miles (25.211 km). The island is part of the Outer Lands region, a coastal archipelago made by the recessional and terminal moraine that resulted from the Wisconsonian Laurentide glacier retreat, about 22,000 years ago.

The Nature Conservancy added Block Island to its list of "The Last Great Places"; the list consists of twelve sites in the Western Hemisphere. About 40 percent of the island is set aside for conservation. Presidents Bill Clinton, Dwight D. Eisenhower, Franklin Delano Roosevelt, and Ulysses S. Grant have visited Block Island. Other famous visitors include Amelia Earhart and Charles Lindbergh, who each made separate trips to the island in 1929.

Block Island is coextensive with the town of New Shoreham. The island is a popular summer tourist destination and is known for its bicycling, hiking, sailing, fishing, and beaches. The island hosts two historic lighthouses: Block Island North Light, on the northern tip of the island, and Block Island Southeast Light, on the southeastern side. Much of the northwestern 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 competitive, week-long sailboat race. On odd years, the event is held by the Storm Trysail Club, and on even years by the Block Island Race Week. 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.