YPEA was the agency responsible for keeping dossiers on the political beliefs of Greek citizens, and as such it was widely feared and despised among the general population.
It was founded in 1958, after the left-wing United Democratic Left managed to win 25% of the popular vote, only nine years after the end of the Greek Civil War.
The man responsible for creating YPEA, Evangelos Kalantzis, was a notorious Deputy Interior Minister who had held important positions in the Metaxas dictatorship.
Throughout its existence, the agency was staffed by police, gendarmerie and civil personnel, but was always led by a retired general of the Hellenic Army.
After the socialist PASOK of Andreas Papandreou became the government in 1981, it installed Lt. General Anastasios Bouras, another officer who had resisted the junta, as the service's director.