| Conventional Long Name: | County (Principality) of Schwarzburg-Sondershausen |
| Common Name: | Schwarzburg-Sondershausen |
| Era: | Middle Ages |
| Status: | Vassal |
| Status Text: | State of the Holy Roman Empire, State of the Confederation of the Rhine, State of the German Confederation, State of the North German Confederation, State of the German Empire, State of the Weimar Republic |
| Empire: | Holy Roman Empire |
| Government Type: | Principality |
| Title Leader: | Prince |
| Year Leader1: | 1697–1716 |
| Year Leader2: | 1909–1918 |
| Event Start: | Partitioned from Schwarzburg |
| Year Start: | 1599 |
| Event End: | German Revolution |
| Year End: | 1918 |
| Event1: | Raised to Principality |
| Date Event1: | 1697 |
| Event Post: | Merged into Thuringia |
| Date Post: | 1920 |
| P1: | House of Schwarzburg#Rulers of SchwarzburgCounty of Schwarzburg |
| Flag P1: | Flagge Fürstentümer Schwarzburg.svg |
| S1: | Thuringia |
| Flag S1: | Flag of Thuringia (state).svg |
| Image Map Caption: | Schwarzburg-Sondershausen within the German Empire |
| Image Map2: | SchwarzburgSondershausen.png |
| Image Map2 Caption: | Schwarzburg-Sondershausen within Thuringia |
| Capital: | Sondershausen |
Schwarzburg-Sondershausen was a small principality in Germany, in the present day state of Thuringia, with its capital at Sondershausen.
Schwarzburg-Sondershausen was a county (earldom) until 1697. In that year, it became a principality, which lasted until the fall of the German monarchies in 1918, during the German Revolution of 1918–1919. After the German Revolution, it became a republic and joined the Weimar Republic as a constituent state. In 1920, it joined with other small states in the area to form the new state of Thuringia.
Schwarzburg-Sondershausen had an area of 862 km2 (333 sq. mi.) and a population of 85,000 (1905). Towns placed in the state were: Arnstadt, Sondershausen, Gehren, Langewiesen, Großbreitenbach, Ebeleben, Großenehrich, Greußen and Plaue.
Raised to Principality in 1697
United under Prince Günther Victor of Schwarzburg-Rudolstadt
| Village | Inhabitants December 1, 1910 | |
|---|---|---|
| Arnstadt | 17,841 | |
| Sondershausen | 7759 | |
| Langewiesen | 3814 | |
| Greußen | 3348 | |
| Großbreitenbach | 3255 | |
| Gehren | 2917 | |
| Geschwenda | 2291 |