The Carnegie School is a school of economic thought originally formed at the Graduate School of Industrial Administration (GSIA), the current Tepper School of Business, of Carnegie Institute of Technology, the current Carnegie Mellon University, especially during the 1950s to 1970s.

The Carnegie School is notable for its interdisciplinary approach, integrating insights from economics, psychology, management science, computer science, public policy, statistics, social sciences, and decision sciences. Faculty and students from these diverse fields collaborated closely, fostering innovative research at the intersection of business, technology, and the social sciences.

Faculty at the Graduate School of Industrial Administration are known for formulating two "seemingly incompatible" concepts: bounded rationality and rational expectations. Bounded rationality was developed by Herbert A. Simon, along with James March, Richard Cyert and Oliver Williamson. Rational expectations were developed by John F. Muth and later translated into macroeconomic theory by Robert Lucas Jr., Thomas Sargent, Leonard Rapping, and others.

Depending on author and context, the term "Carnegie School" can refer to either both branches or only the bounded rationality branch, sometimes with the qualifier Carnegie School of organization theory. The commonality between both branches is the use of dynamic optimization and forecasting techniques derived from production theory and expectations, and the early use of computers to solve planning and optimization problems. Along with other, mostly Midwestern universities, the rational expectations branch is considered part of freshwater economics, while the bounded rationality branch has been credited with originating behavioral economics and economics of organization.

The Graduate School of Industrial Administration (GSIA) at the Carnegie Institute of Technology (CIT) in Pittsburgh, Pennsylvania was founded in the late 1940s, after receiving a grant by William Larimer Mellon Sr. to enable graduate instruction in business and economics for the engineers the CIT already produced. This superseded an initial attempt to "restart" the economics department, which had lapsed during World War II. The founding dean was George Leland Bach, initial faculty hires included William W. Cooper and Herbert A. Simon. Other early appointees were Abraham Charnes, Richard Cyert, James G. March, Franco Modigliani and Merton Miller.

GSIA was set up as a "new look" business school, moving beyond the case-based method of instruction popularized by Harvard Business School, to incorporate scientific methods of management. The economics faculty was folded into the business school.

In 1956, Carnegie Tech obtained an IBM 650 computer, jointly acquired by GSIA and the engineering and mathematics departments, but housed in the basement of the business school. Along with the computer, Allen Newell and Alan Perlis joined the faculty, with Perlis being put in charge of the computing facilities. Edward Feigenbaum, at the time a student at Carnegie Tech, was sufficiently intrigued to transfer to GSIA. All three, along with Herb Simon, would later receive the Turing Award for their contributions to computer science.

The focus of the research was on organizational behavior and the application of decision analysis, management science, and psychology as well as theories such as bounded rationality to the understanding of the organization and the firm.