Robert M. Solow (August 23, 1924- ) is an American economist particularly known for his work on the theory of economic growth. He was awarded the Nobel Prize in Economics in 1987. Solow was born in Brooklyn, New York. He served in the United States Army from 1942 to 1945. He earned his doctorate in economics at Harvard University, studying under Wassily Leontief. Together with Paul Samuelson, he formed the core of the M.I.T. economics department which has been widely viewed as the "mainstream" of the post-war period.

Solow's model of economic growth, often known as the neo-classical growth model, allows the determinants of economic growth to be separated out into increases in inputs (labour and capital) and technical progress. A common prediction of neoclassical growth models is that an economy will always move towards a steady state (or "balanced growth path").

In this steady state the growth rate of the economy depends only on the rate of technological progress. Policy measures like tax cuts or investment subsidies are believed to have no effect on this long-run growth rate. Using his model, Solow calculated that about four fifths of the growth in US output per worker was attributable to technical progress.

Neoclassical growth theory boils down to saying that long run economic growth comes from technological progress. The next step is then to ask "Where does technological progress come from?", and this question has led to the development of endogenous growth theory.

Since Solow's inital work in the 1950s, many more sophisticated models of economic growth have been proposed, leading to varying conclusions about the causes of economic growth. In the 1980s efforts have focused on the role of technological progress in the economy, leading to the development of endogenous growth theory (or new growth theory).

“But part of the job of economics is weeding out errors. That is much harder than making them, but also more fun.”

-Robert Solow