The order began in the early thirteenth century in Languedoc (France), founded by the Spanish canon Dominic de Guzmán for the purpose of fighting the spread of the Cathar heresy. Dominic and his companions chose to fight the heretical doctrines both by preaching and by the example of severe personal asceticism, living in poverty and begging for their food. Since, in order to refute the heterodox doctrines, it was necessary for the preachers, besides being exemplarily poor, to have also a solid cultural background, Dominican convents became important centers of theological and Biblical studies, and some of the most important medieval theologians, such as Thomas Aquinas and Albert the Great, belonged to the order.
The first friars arrived in Siena with the founder Saint Dominic around 1215-16, when he went to Rome to see Pope Honorius III for approval of the Rule of the Order of Preachers, which was officially decreed on 22 December 1216. At first, the group of friars were given hospitality on the south side of the city; then, in 1225, the Sienese gentleman Fortebraccio Malavolti gave them the Camporegio hill so they could build a church and their convent there.
The settlement of Dominicans in the city of Siena was due mainly to the presence of the Studium (which became the University) and to the fact that the Order had set itself the task of combating heresy and pursuing the salvation of souls by means of preaching and teaching. Precisely because of their teaching charism, Dominicans are present in the main university towns of Europe.
Both the church and the convent were finished around 1262-1265. The church was very big because it had to answer the needs of a new evangelization, and thus had to be able to hold the great crowds of people who came to hear the preaching of the Preaching Friars, or the Dominicans.
With Grand Duke Leopold’s reforms, the convent of San Domenico was suppressed, and in 1786 it became a Cassinese Benedictine monastery, until 1912 when the Benedictines left; thus in 1920 the Dominicans were able to return to their church and convent, where they still reside today and safeguard the memory of the spirituality of Saint Catherine of Siena.