Lawrence R. Klein (born September 14, 1920,Omaha,Nebraska, U.S.—died October 20, 2013, Gladwyne, Pennsylvania) was an American economist whose work in developing macroeconometric models for national, regional, and world economies won him the 1980Nobel Prize in Economic Sciences.

After graduating from theUniversity of California, Berkeley, in 1942, Klein studied under economistPaul Samuelson at theMassachusetts Institute of Technology, taking a Ph.D. in 1944. From 1944 to 1947 he was involved in econometric research at theUniversity of Chicago, and from 1948 to 1950 he was on the staff of the National Bureau of Economic Research. Subsequently he was associated with the Survey Research Center of theUniversity of Michigan (1949–54) and the Institute of Statistics at theUniversity of Oxford (1954–58). Klein joined the faculty of theUniversity of Pennsylvania in 1958 and later became Benjamin Franklin Professor of Economics and Finance at the university’s Wharton School (1968–91; later emeritus). Klein was one of the pioneers in buildingmacroeconomic models. One of his earliest successes was in forecasting economic conditions at the end ofWorld War II. Whereas many economists speculated that the war’s end would bring anotherdepression, Klein predicted that the unsatisfied demand for consumer goods throughout the war, combined with the purchasing power of returning soldiers, would likely prevent a depression; his prediction was right.

Klein’s research produced a series of increasingly detailed and sophisticated models of economic activity. TheWharton Models found wide use in forecastinggross national product, exports, investment, andconsumption. A more ambitious effort, theLINK project, incorporated data gathered from a large number of industrialized, centrally planned, and developing countries to forecast trade and capital movements and to test the effects of proposed changes in political and economic policies. The project is discussed in the 1995 bookEconomics, Econometrics and the LINK, edited by Manoranjan Dutta.