Manuel Baldomero Ugarte was born in San José de Flores, now part of the city of Buenos Aires, on 27 February 1875.
His only brother, Floro Melitón Ugarte, born nine years later than Manuel, was a music composer and director of the famous Colón Theatre in Buenos Aires.
His public life began alongside Leopoldo Lugones, Roberto Payró, Alberto Gerchunoff, Manuel Gálvez, and José Ingenieros.
He founded La revista literaria, which, among others, published the works of Rubén Darío and Ricardo Jaimes Freyre.
Rubén Darío, Miguel de Unamuno, Delmira Agustini, R. Blanco Fombona, Henri Barbusse, Manuel Gálvez, Haya de la Torre, José Vasconscelos, Blanca Luz Brum, and many others, can be considered his friends and correspondents.