Ernesto Cruz was born in León, Nicaragua in 1931. [2 ] After spending his youth in Managua, Cruz moved to Silver Spring, Maryland, USA for boarding school. [3 ] In 1956 Cruz earned his law degree from the National University of Nicaragua.
Cruz was born in San Juan de Flores in Honduras. His Father was Carlos Alberto Cruz and his mother Elisa Ucles Rosales. He was the eldest son, his brothers were: Herlinda, Carlos, Raul, Rene and Marta.
V roce 1957 byl členem vojenské junty, která se uchopila moci v zemi. Poprvé se stal prezidentem po vojenském puči, který se uskutečnil 10 dní před plánovaným termínem voleb.