Smirnov obtained his first degree from Moscow U in 1926. His doctoral thesis (1938) served as a foundation for his subsequent work on the theory of non-parametric tests. His career was spent at the Steklov Mathematical Institute of the USSR Academy of Sciences. His forte lay in solving difficult computational problems using ingenious methods. He is remembered today for his 1939 work on the distribution of the test statistic proposed by Kolmogorov in 1933.