A former rebel leader, Salvador Sanchez Ceren won the presidential run-off of March 2014 by a narrow margin.
As presidential candidate of the left-wing Farabundo Marti Liberation Front (FMLN), he beat Norman Quijano of the conservative Arena party by less than a quarter of a percentage point, becoming the first former guerrilla to lead the Central American country.
In his inauguration speech, he promised to fight corruption and violence, and "to serve as president of all Salvadorans".
Mr Sanchez Ceren, 69, also promised that "security, employment and education" would be the priorities of his government.
A former teacher, Mr Sanchez Ceren rose to become one of the FMLN's top commanders during the country's bloody 1979-1992 civil war. The FMLN became a political party after the 1992 peace accords.
As president, he succeeds Mauricio Funes, a former journalist whose FMLN government elected in 2009 ended two decades of conservative rule, mostly under Arena. Mr Sanchez Ceren was vice-president in the Funes government.
Among the challenges he faces are dealing with a resurgence of violence by criminal gangs, a struggling economy, and endemic poverty.
President: Salvador Sanchez Ceren