Ivan Yordanov Kostov (Иван Йорданов Костов) (born December 23, 1949 in Sofia) was Prime Minister of Bulgaria from May 1997 to July 2001 and leader of the Union of Democratic Forces (UDF) between December 1994 and July 2001.
Ivan Kostov graduated in Economics from the Karl Marx Higher Institute of Economics (now University of National and World Economy) in Sofia in 1974, and later earned a Ph.D. in Mathematical Modeling of Economic Processes from the Sofia University. He had worked as associate professor at Sofia Technical University, and entered politics after the collapse of the Berlin Wall and the fall of the Bulgarian communist dictator, Todor Zhivkov. Kostov became an economic expert for the Union of Democratic Forces (UDF), the newly created major anticommunist party, in 1990. His political career began as Member of Parliament in the 7th Grand National Assembly in 1990 (he has been re-elected to Parliament ever since) and he went on to become Bulgaria's Finance Minister in the two consecutive governments of Dimitar Popov (December 1990 – October 1991) and Filip Dimitrov (November 1991 – December 1992).
Kostov was elected chairman of the UDF in 1994 and, after winning the May 1997 elections, became Bulgaria's Prime Minister, his cabinet being the first Bulgarian post-communist government to serve its full 4-year term, due to having a large majority. He is sometimes credited for turning around his country's fortunes and establishing a path towards Bulgaria's complete integration with the West. Under his government, long-delayed economic reforms were carried out, privatization of state-owned enterprises was carried on a large scale and the country started long-sought accession talks with the European Union (which Bulgaria joined on January 1, 2007).
However, reformist policies led to increased unemployment and his privatisation policies were widely criticised as being harmfull to Bulgaria's interests. There was also widespread allegation of corruption in his cabinet and he was accused of shielding ministers in his cabinet from investigation. His government is also often blamed for the widely criticised health care reforms and the decline in education. Ultimately the UDF lost in the June 2001 election to the National Movement Simeon II. Kostov resigned as chair of the UDF and eventually left the party to establish, in 2004, a new political force, Democrats for a Strong Bulgaria (DSB).