Exchange mobility is the sociological concept that suggests society is made up of classes and that these classes maintain a relatively static number of people. Should a set number of people move upward from the middle class, an equal number is expected to move down from the upper class.
The concept of exchange mobility is also commonly referred to as relative mobility or circulation mobility. It is part of the process of social mobility that defines the social position of a given person, class, group or nation, as they pertain to social structure. The idea of exchange mobility is not a proven standard, as many factors affect the social class structure and create variations accordingly.