Rural schoolteacher turned rebel commander Salvador Sanchez Ceren has been sworn in as president of El Salvador.
Sanchez Ceren, 69, promised to govern "with honesty, austerity, efficiency and transparency" at the inauguration ceremony on Sunday attended by leaders from 13 countries.
"After long years of fighting for justice and democracy in my country, I receive the presidential sash with humility and profound respect, with a commitment to exercise the presidency for all Salvadorans," he said.
Sanchez Ceren belonged to the Farabundo Marti National Liberation Front (FMLN) and rose to become one of the rebel group's top commanders, under the nom de guerre Leonel Gonzalez, during the country's bloody 1979-1992 civil war.
He was elected president on March 9, defeating the conservative Nationalist Republican Alliance (ARENA) party candidate Norman Quijano by less than a quarter of a percentage point.
In doing so, he became the fourth former leftist rebel leader to be elected president in Latin America after Daniel Ortega in Nicaragua, Jose Mujica in Uruguay, and Dilma Rousseff in Brazil.
Sanchez Ceren succeeded Mauricio Funes, a former journalist whose FMLN government in 2009 ended two decades of conservative rule, mostly under ARENA. Sanchez Ceren was Funes's vice president.
He inherits a country beset by violent gangs and poverty, which affects 40 percent of the population of the tiny Central American country.