This fund gathers together the archives of Arti (218 pieces, from 1316 to 1873), of Opere di chiese e conventi (111 pieces, from 1401 to 1811), and of some famiglie o persone (Baldini, Buonamici, Campani, Martelli, Martini, Mazzoni, Novellucci, Pacini, Vai, Zarini).

The private and family scale is proved by documentary evidence of archives acquired afterwards, such as the archive Salvi Cristiani (869 pieces, from XV to XIX century), the archive Vai Guicciardini (1150 pieces, from 1510 to 1955, mostly concerning the administration of estates) and the papers of Pietro Cironi (9 pieces, from 1799 to 1862).

The fund of Casa pia dei Ceppi (3711 pieces, from 1282 to 1885) includes the archives of two important charities: the Ceppo Vecchio, established in 1282 following a bequest "pro remedio anime" of Monte Pugliesi and aiming mainly at the relief for the so-called "shameful poverty", and the Ceppo Nuovo, founded in 1410 following the will of Francesco di Marco Datini, to which he allocated his entire patrimony allowing also the intact preservation of his archive.

From the repository of Casa pia dei Ceppi comes also the Archivio Datini (1193 pieces, from 1361 to 1411, including documents dated up to 1443), unique testimony to the commercial, industrial and banking activity of a merchant of the second half of the XIV century. From 1545, the two bodies - and therefore the two archives - were reunited into the same institution (Ceppi riuniti) as per Cosimo I de' Medici.

At the end of XVIII century, this body - considered as a major one in Tuscany due to its importance and richness - was assigned with the administration of the abolished Patrimonio Ecclesiastico, and also of all the archives of convents and religious societies abolished by Pietro Leopoldo in 1783-1784, following the policy of ecclesiastical reforms that created particularly intense and hard-fought moments in Prato, due to the presence of the reforming bishop Scipione de' Ricci (3852 pieces with acts from 1309 to 1789, and 87 parchments from 1274 to 1682). Documentary evidence of the management and liquidation of the Ecclesiastical Patrimony is shown in the archive of Resti del Patrimonio Ecclesiastico (279 pieces, from 1776 to 1933).