In common with many rural communes, Pair-et-Grandrupt suffered a prolonged population decline which set in after the agricultural depression which started in the 1870s and from which there was no sustained recovery until the second half of the twentieth century.

Between 1968 and 1999 registered population (excluding double counting in respect of students and others with two registered homes) increased from 200 to 439, and the construction of a modern water supply network supported by appropriate pipes and pumps has made it possible to build on formerly dry mountainside sites, and at levels of housing density which in earlier centuries was not possible simply because the nearest usable water supply was insufficient and/or too far away.

Beside the church at Bertrimoutier is a large cemetery-ossuary which for centuries has welcomed the mortal remains of people from a wide area along the southern flank of the Ormont Hills.

During the early and middle Medieval periods, it is thought that Le Pair Grandrupt and Villers were part of a single extended village in the Duchy of Lorraine.

Between the end of the Duchy of Burgundy in 1477 and the final incorporation of Lorraine into France that followed the death of the Last Duke in 1766, there were several French invasions and periods of occupation affecting Lorraine and other de facto buffer states between France and the Holy Roman Empire, but relatively untroubled in their mountain seclusion the administrative arrangements of the hamlets of Le Pair, Grandrupt and Vanifosse remained unchanged except that in 1710 the bailiwick was switched to Saint-Dié.