one of a Nicaraguan group that overthrew President Anastasio Somoza Debayle (Somoza Debayle, Anastasio) in 1979, ending 46 years of dictatorship by the Somoza family. The Sandinistas governed Nicaragua from 1979 to 1990. Sandinista leader Daniel Ortega was reelected as president in 2006.

Named for César Augusto Sandino (Sandino, César Augusto), a hero of Nicaraguan resistance to U.S. military occupation (1927–33), the FSLN was founded in 1962 by Carlos Fonseca Amador, Silvio Mayorga, and Tomás Borge Martínez as a revolutionary group committed to socialism and to the overthrow of the Somoza family. Over the next 10 years the FSLN organized political support among students, workers, and peasants. By the mid-1970s its attacks on the Nicaraguan National Guard from sanctuaries in Honduras and Costa Rica were serious enough that Somoza unleashed bloody reprisals against the Sandinistas. Fonseca and Mayorga were killed, and the FSLN split into three tendencias, or factions, that differed over whether the group should organize revolutionary cells only in the cities, continue to gradually accumulate support throughout the country, or coalesce with other political groups in the growing rebellion. The Nicaraguan revolution of 1978–79 reunited the Sandinistas under the third tendencia, headed by Daniel and Humberto Ortega Saavedra, and the FSLN, now numbering about 5,000 fighters, defeated the National Guard and overthrew Somoza in July 1979.

A nine-member National Directorate, composed of three comandantes from each faction, was then set up to lead the FSLN and set policy for a governing junta that was headed by Daniel Ortega (Ortega, Daniel). Once in power in Nicaragua, the FSLN organized itself into local and regional committees and built up support through mass organizations of workers, young people, and other groups. To fight off the attacks of the counterrevolutionary forces known as the contras, who were based in Honduras and were in part armed and financed by the United States, Humberto Ortega created the 50,000-strong Sandinista Popular Army, and Tomás Borge organized a secret-police force to guard against espionage and dissent. The resignations of various non-Marxist members of the Sandinista leadership, chiefly over issues of political rights, pushed the party and Nicaragua progressively to the left, and both became dependent on the support of the Soviet Union and Cuba.

The Sandinista government confiscated the Somoza family's vast landholdings and nationalized the country's major industries, but the central planning typical of Soviet-style socialist economies was never adopted, and small and medium-sized private farms and businesses were tolerated. Having committed itself to political pluralism, the FSLN grudgingly tolerated moderate opposition groups and agreed to elections only after considerable pressure at home and abroad. In 1984 the FSLN won more than 60 of 96 seats in a new National Assembly and sent Daniel Ortega to the presidency in an election that was widely criticized for its lack of safeguards for opposition parties. In 1990, however, the Nicaraguan populace, weary of war and economic depression, voted for the 14 parties of the National Opposition Union, which formed a government while the Sandinistas relinquished power.

Though reduced to an opposition party, the FSLN retained a considerable power base in the country's army and police forces. It also performed strongly in national elections; in 1996 the Sandinistas won 37 percent of the vote in parliamentary elections, and in 2001 the party captured 42 percent of the vote and won 43 seats in the 90-seat National Assembly. The FSLN regained power after its leader, Ortega, was reelected to the presidency in 2006. The party also won a plurality of seats in the legislature.