He then took a job assisting the philologist J. J. Smith [af] in editing Die Huisgenoot, but he moved shortly thereafter over to the Nasionale Pers to be head of the publication department.
He also worked under C. G. N. de Vooys at the University of Utrecht on his dissertation Die Afrikaner en Sy Taal, 1806-1875, for which he received the Hertzog Prize for scholarly prose (what is more, the award had existed until then; it was expressly created in order to honor him with it).
In 1950 he became head of the Department of Dutch and Afrikaans and Hofmeyr-Professor, and in 1965 retired as emeritus professor to pursue linguistic and artistic scholarship without the pressure of university administration.
While others in South Africa, and to a lesser extent the Netherlands and Belgium, were still discussing origin of Afrikaans at a theoretical level only, Scholtz had been collecting and analyzing as much data as were available.
He was a member of the South African Academy of Arts and Sciences, the Maatschappij der Nederlandsche Letterkunde, the International Centre for Onomastics, and the Linguistic Society of America.
The Kaapse Drie-Eeuestigting added to this and celebrated his work on the Irma Stern Trust with an honorary award in 1972.
In 1934 his publishing life began with the article "Afrikaanse geskrifte van Louis Henri Meurant uit die jare 1844-1850" in Tydskrif vir Wetenskap en Kuns, Jg.
Scholtz's monographs on Strat Caldecott, Pieter Wenning, D. C. Boonzaier, Moses Kottler, and Katrine Harries remain authoritative.
In 1923, while at the National Press, he met the "famous and feared" D. C. Boonzaier, cartoonist and supporter of the fine arts in Cape Town.
Eventually, his circle of artist-friends was to include the painters Enslin du Plessis, Jean Welz, Florence Zerffi and Irma Stern, the graphic artist Katrine Harries, and, less intimately, Hendrik Pierneef, Erich Mayer, and Ruth Prowse, the members of a school of South African Impressionism in the years 1915–1935.
'n Ondersoek na die taal- en literêr-historiese arbeid van J. du P. Scholtz.