Kuznets's early work on cyclical fluctuations in retail and wholesale trade identified cycles of 15-20 years' duration, which have ever since been labelled ‘Kuznets's cycles’. Later work on growth patterns in different countries identified an inverse U-relationship between per capita income and the inequality of income distribution, such that in poor countries inequality rises with income but in rich countries it falls as income rises.

Kuznets was born in Kharkov (now in the Ukraine) and rose at an early age to become head of a statistical office in the Ukraine under the Bolsheviks. In 1922 he emigrated to the USA and entered Columbia University, receiving his BSc in 1923, his MA in 1924, and his PhD in economics in 1926. Joining the National Bureau of Economic Research, headed by his PhD supervisor Wesley Mitchell, he launched upon a study of national income. In 1930 he took up a teaching post at the University of Pennsylvania, where he remained as professor until 1954, interrupted only by two years as associate director of the Bureau of Planning and Statistics of the US War Production Board, during World War II. In 1954 he moved to Johns Hopkins University as professor of political economy, moving again in 1960 to Harvard University, where he remained until his retirement in 1971.

He was president of the American Statistical Association in 1949, the American Economic Association in 1954, the Falk Programme for Economic Research in Israel (1953-63), and he received the Francis A Walker Medal of the American Economic Association in 1977.

His works include National Income and Capital Formation 1919-35 (1941), National Product Since 1869 (1946; with E Jenks and L Epstein), Economic Growth and Structure: Selected Essays (1965), Modern Economic Growth: Rate Structure and Spread (1966), and Growth, Population and Income Distribution: Selected Essays (1973).