Vieques (/viːˈeɪkɨs/; Spanish pronunciation: [ˈbjekes]), in full Isla de Vieques, is an island–municipality of Puerto Rico in the northeastern Caribbean, part of an island grouping sometimes known as the Spanish Virgin Islands. Vieques is part of the United States Commonwealth of Puerto Rico, but, like the rest of Puerto Rico, retains strong influences from 400 years of Spanish ownership.

Vieques lies about 8 miles (13 km) east of the Puerto Rican mainland, and measures about 21 miles (34 km) long by 4 miles (6 km) wide. Its two main towns are Isabel Segunda (sometimes written "Isabel II"), the administrative center on the northern side of the island, and Esperanza on the southern side. At peak,^{[clarification needed]} the population of Vieques is around 10,000.

The island's name is a Spanish spelling of a Native American word said to mean "small island". It also has the nickname "Isla Nena", usually translated from the Spanish as "Little Girl Island", alluding to its perception as Puerto Rico's little sister. During the colonial period, the British name was "Crab Island".