The Secretary of State for Protestant Affairs (French: Secrétaire d'État de la Religion Prétendue Réformée, or R.P.R., the "So-called Reformed Religion"), was the secretary of state in France during the "Ancien Régime" and Bourbon Restoration in charge of overseeing French Protestant affairs. From 1749 on, the position was combined with the position of Secretary of State of the Maison du Roi.
During the preparation and implementation of the Edict of Nantes (finalized in 1598), an administrative department was created to oversee Protestant affairs. By a royal decision in 1588, one of the four secretaries of state of Henry III, Forget de Fresne, was given the responsibility of negotiating with the provinces which had large Huguenot populations (Languedoc, Dauphiné, Orléanais, Maine, Anjou, Poitou, Saintonge, Angoumois). Trusted by Henry IV, Forget de Fresne became the principal author of the Edict of Nantes (which he co-signed), and organizer of the department of Protestant affairs.
From 1610 to 1775, this position was held by members of the Phélypeaux family.
Until the revocation of the Edict of Nantes (1685), the secretary – whose oversight covered a huge geographical area – was especially concerned with communicating with provincial governors, intendants and bishops regarding real or imagined violations of the provisions of the Edict, and disputes concerning the demolition of temples and religious freedom. As public opinion in the 17th century became increasingly hostile to the Huguenots, the secretaries fulfilled their duties in applying more rigorous measures on the Protestants. In 1685, the then-secretary, Balthazar Phélypeaux, countersigned the Edict of Fontainebleau.