Another important welfare body is constituted by Ospedale della Misericordia e Dolce, whose archive - consisting of 3672 pieces from 1245 to XX century and of 107 parchments - preserves the papers of the main town hospitals founded in the Middle Ages and reunited afterwards in XVI century, as well as the records of many merchants and craftsmen that, in their will, left some great bequests of money to the Hospital and, in addition to that, thanks to books of memories and "remembrances", also a living testimony of their existence.

The outline of welfare institutions is finally completed by the archives of Monte di Pietà (169 pieces, from 1549 to 1933), of Venerabile Arciconfraternita della Misericordia (202 pieces, from 1574 to 1945) and of Conservatorio delle Pericolanti poi di S. Caterina (115 pieces, from 1688 to 1902).

The State Archives also gather the archives of Institutions or local associations having cultural purposes, such as the archive of Accademia degli Infecondi later on become Società dei Misoduli (30 pieces, from 1712 to XIX century), and of Teatro Metastasio (90 pieces, from 1826 to 1938).

The documentary patrimony of the State Archives can always be enhanced, as the Archives are appointed as the institution suited to receive the archives of the peripheral state offices present within the provincial territory (as it happened to the archives of Pretura, Commissariato di P.S. and Ufficio del Registro), and also because the Archives gather the voluntary repository of archives belonging to public authorities that are not state-owned (e.g. Comune di Vernio, the current Ospedale della Misericordia, etc.), of individual persons and most of all, due to the peculiar production network typical of Prato, of industrial companies (as the archive of Razzoli).