The first area outside the empire to officially accept the Reformation was the kingdom of Denmark-Norway under King Christian III (r. 1536–1559). In the 1530s, the king officially broke with the Catholic Church, and most clergy followed. The process went smoothly in Denmark, but in northern Norway and Iceland (which Christian also ruled), there were violent reactions, and Lutheranism was only gradually imposed on a largely unwilling populace.

In Sweden, Gustavus Vasa (r. 1523–1560), who came to the throne during a civil war with Denmark, also took over control of church personnel and income. Protestant ideas spread, though the Swedish Church did not officially accept Lutheran theology until later in the century.