When Transylvania became a Habsburg province, freedom of religion was permitted, and during this time the Reformed nobles protected Calvinism.

The Reformed Diocese of Transylvania has official connections with the Swiss, Dutch and German Calvinists.

From 1940 to 1944, Hungary held Northern Transylvania, before Romania retook the area at the end of World War II.

In 1989, with the fall of the regime, the situation changed: parishes were rebuilt, theological schools reopened and dozens of new congregations were formed.

[8] The church has 16 presbyteries (egyházmegye – in Hungarian), at Brașov, Dej, Căpeni, Reghin, Petroşani, Huedin, Târgu Secuiesc, Cluj-Napoca (two), Fântânele, Târgu Mureș (two), Aiud, Sfântu Gheorghe, Cristuru Secuiesc and Turda.

The Romanian Reformed Church's highest decision making institution is the General Assembly, the chairmen are the bishop and the main janitor (gondnok in Hungarian) The two dioceses, the Transylvanian and the Kiralyhágómellék ones, have separate bishops and janitors; in the General Assembly, they enjoy equal rights.

Alongside the early creeds, the Heidelberg Catechism and the Second Helvetic Confession, John Calvin's Institution and Les Ordonances [sic] (about church government) are widely used.