Bad Arolsen is a small town in northern Hesse, Germany, in Waldeck-Frankenberg district. From 1655 until 1918 it served as the residence town of the Princes of Waldeck-Pyrmont and then until 1929 as the capital of the Waldeck Free State. The International Tracing Service has its headquarters in Bad Arolsen.

The County of Waldeck was a state of the Holy Roman Empire and its successors from the late 12th century until 1929. In 1349 the county gained Imperial immediacy and in 1712 was raised to the rank of principality. After the dissolution of the Holy Roman Empire in 1806 it was a constituent state of its successors: the Confederation of the Rhine, the German Confederation, the North German Confederation, and the German Empire. After the abolition of the monarchy in 1918, the renamed Free State of Waldeck-Pyrmont became a component of the Weimar Republic until divided between Hannover and other Prussian provinces in 1929. It comprised territories in present-day Hesse and Lower Saxony (Germany).