Theory of Constraints (TOC) is an overall management philosophy that aims to continually achieve more of the goal of a system. If that system is a for-profit business, then the goal becomes one of making more money, in the present as well as in the future. TOC consists of two primary collections of work: 1) The five focusing steps and their application to operations; 2) The thinking processes and their application to project management and human behavior.

According to TOC, every organization has one key constraint which limits the system's performance relative to its goal. These constraints can be broadly classified as either an internal constraint or a market constraint. In order to manage the performance of the system, the constraint must be identified and managed correctly.

The publicity and leadership behind these ideas has been dominated by Eliyahu M. Goldratt , the creator of ToC, through a series of books, seminars and workshops.