Palatinate-Lautern was a state of the Holy Roman Empire based around Kaiserslautern and Neustadt an der Weinstrasse in the south of modern Rhineland-Palatinate, Germany.
Palatinate-Lautern was partitioned from the Electorate of the Palatinate in 1576 after the death of Frederick III, Elector Palatine for his younger son John Casimir. John Casimir accepted Huguenot refugees from France and Calvinist exiles from the Palatinate, making it a Calvinist stronghold. John Casimir was convinced by Queen Elizabeth I of England to establish the Protestant League in Germany against the Catholic states and the Holy Roman Emperor, making it one of the most influential states in its day. John Casimir died in 1592 without heirs, so Palatinate-Lautern was returned to the Palatinate.