Beginning in the late eleventh century and ending in the mid-fifteenth century, ars dictaminis consisted of a highly formalised code of rules governing the composition of prose letters in Latin and, sometimes towards the end of the period, in the vernacular. While acknowledging that letters could also be composed in verse or in prosametron, a mixture of prose and poetry, the manuals of the ars focused solely on prose communication. If they emphasised eloquent expresion, the goal of the instruction was eminently practical: to attain the purpose for which the letter was being sent.

The ancients never developed a theoretical approach to letter-writing, claiming as they did that the letter needed the flexibility of conversation. In practice, in the case of letters having the status of official or public communications, however, they seem to have followed the rules governing oratory for which textbooks like Cicero's De inventione and the Pseudo-Ciceronian Ad Herennium abounded. By the twelfth century, especially in Italy, the word dictamen came to be intimately associated with the rules of letter-writing while the professional writer of letters or teacher of the art became known as the dictator. Whereas in practice the ancients distinguished between public and private letters, medieval ars dictaminis tended to ignore any distinction and assimilated all letters to the oratorical model. In Italy the generation of Peter Damian (d. 1073) and Pope Gregory VII (d. 1085) was the last until the advent of humanism in the fourteenth century to give a personal tone to correspondence.