Rein Taagepera (born 28 February 1933) is an Estonian-American politician and political scientist.

Born in Tartu, Estonia, Taagepera fled from occupied Estonia in 1944. Taagepera graduated from high school in Marrakech, Morocco and then studied physics in Canada and the United States up to a Ph.D. from the University of Delaware in 1965. Working in industry until 1970, he received another M.A. in international relations in 1969 and switched to academe as a political scientist at the University of California, Irvine, where he stayed for his entire American career.

In 1991, Taagepera returned to Estonia as founding dean of a new School of Social Sciences at the University of Tartu, which merged into a full-fledged faculty in 1994, and where he also became Professor of Political Science, 1994-1998.

In 1991, he was also a member of the Estonian Constitutional Assembly, and in 1992, he ran as a presidential candidate against Arnold Rüütel, the current President, and Lennart Meri, who won then; Taagepera came in third with 23% of the popular vote. In 2003, Taagepera agreed to serve for half a year, more or less formally, as the founding chairman of a new political party, Res Publica, which won the general elections that year and lead the governing coalition under Prime Minister Juhan Parts until April, 2005. Taagepera has recently distanced himself from Res Publica.

Taagepera served as President of the Association for the Advancement of Baltic Studies (1986-1988); he received the American Political Science Association's Hallett (1999) and Longley (2003) Awards and the Estonian National Science Prize, Social Science Category (1999).

Taagepera's theoretical scholarly work, which mainly deals with electoral systems, is heavily quantitative and modelling in character and strongly informed by the epistemology of his previous field, physics; the quantitative approach is also is his general attitude towards political science as a scholarly discipline. His studies of Estonian and generally Baltic history, politics, and culture, on the other hand, are very personal and take strong normative positions. Taagepera has also written award-winning prose.

Key Publications:

• Seats and Votes: The Effects and Determinants of Electoral Systems, 1989, co-author
• Estonia: Return to independence, 1993
• The Baltic States: Years of Dependence, 1940-1990, 2nd edn. 1993, co-author
• The Finno-Ugric republics and the Russian state, 1999