His parents were nobles; at a very early age he entered the Dominican Order at St Steven’s Priory, Salamanca.

Its severe discipline, however, affected his delicate constitution and he was transferred to the convent of St. Paul in Peñafiel where he was professed in 1495.

On the completion of his studies in Alcalá, and later at the Colegio de San Gregorio of Valladolid University, he taught philosophy and theology.

About the same time he was appointed regent of studies and for two terms filled the office of rector in San Gregorio College.

There he made the acquaintance of Charles V, Holy Roman Emperor who chose him for his confessor and later, with papal sanction, offered him the See of Osma, for which he was consecrated on 8 June 1524.