In 1948 he started as theater critic and film in the newspaper El País year he held for a decade with knowledge, intuition and great explanatory clarity.
In 1949 Larreta founded, along with Susana Pochintesta, the independent group Club of Theater directing both his own works as a happy family Electra of Jean Giraudoux .
He paused for two years in Italy between 1954 to 1955 where, besides deepening their theatrical training, he worked as an assistant of the Italian master Giorgio Strehler at the Piccolo Teatro.
On his return from Italy he conducted pieces of Federico Garcia Lorca Dona Rosita the Spinster and The House of Bernarda Alba and The Brothers Karamazov by Fyodor Dostoyevsky .
At the end of 1959 and for a few months in 1960 he held the artistic direction of the National Comedy that soon leaves because of the paralyzing bureaucracy of the Committee on Municipal Theatres.
In 1961 he founded the TCM (Theatre of the City of Montevideo), along with two leading figures of the Uruguayan theater, China Zorrilla and Enrique Guarnero performing in Buenos Aires, Paris and Madrid .
In Paris they performed at the Theatre of Nations and the Spanish presented in the Spanish Theater: The Shoemaker’s Prodigious Wife of Federico Garcia Lorca, in the regime of Franco , Family, Hand holy and persist until death of Lope de Vega by who won the Spanish Critics Award.