Paul Samuel Reinsch (June 10, 1869–January 26, 1923), was an American political scientist and diplomat. He was born in Milwaukee, Wisconsin of German-American parents. Reinsch graduated at the University of Wisconsin–Madison in 1892, attended the school of law at the same institution and after graduating in 1894, was admitted to the bar and practiced law at Milwaukee for some time.
He returned to the University of Wisconsin–Madison for additional schooling in 1895. He was also employed there as an assistant professor of political science. In 1913 he became the United States Minister to China, a position he held until 1919. Before and after that date he served as delegate to various international conferences.
- The Common Law in the Early American Colonies, (1899)
- World Politics at the End of the Nineteenth Century, (1900)
- Colonial Government, (1902);
- Colonial Administration, (1905)
- American Legislatures and Legislative Methods, (1907)
- Readings on American Federal Government, (1909)
- Readings on American State Government, (1911);
- Civil Government, (1909)
- Intellectual and Political Currents in the Far East, (1911)
- Public International Unions (1911)
- An American Diplomat in China, (1922)
He was a contributor to the New International Encyclopedia.