[Excerpt] Our main purpose in this survey is, therefore, to provide a somewhat unified setting within which the basic features of the theory of income mobility measurement can be outlined. Our aim is to provide a (subjectively) selective introduction to the literature on income mobility, and thereby shed some light on particular aspects of mobility measurement. Consequently, the present study should not be viewed as an exhaustive survey of the related literature. It is rather a very concise account of some key elements of the theory of income mobility measurement.