Steklov Institute of Mathematics or Steklov Mathematical Institute (Russian: Математический институт имени В.А.Стеклова) is a research institute based in Moscow, specialized in mathematics, and a part of the Russian Academy of Sciences. It was established April 24, 1934 by the decision of the General Assembly of the Academy of Sciences of the USSR in Leningrad. The institute is named after Vladimir Andreevich Steklov.
In 1940 it was moved to Moscow, but its old building became its Department in Leningrad. Today, that department has become a separate institute, called the St. Petersburg Department of Steklov Institute of Mathematics of Russian Academy of Sciences or PDMI RAS, located in Saint Petersburg, Russia. The name St. Petersburg Department is misleading, however, because the Petersburg Department is now independent and retains no ties with the Steklov Mathematical Institute.
In 1966, the Moscow-based Keldysh Institute of Applied Mathematics (Russian: Институт прикладной математики им. М.В.Келдыша) split off from the Steklov Institute.