The concept of social mobility, as many other concepts, that underpin modern sociology is undergoing substantial evolution under the influence of change that occurs in modern societies often characterized as "fluid" and unstable. The mobility theory has been used by sociologists to diagnose the state of society, discover the directions to which it was heading. Early at the start of mobility studies one of the founders of social mobility theory called for a complex view of it, proposed to view as complex, inter-related moves of people, objects and ideas. P. Sorokin called for a study of mobility that incorporated not only human beings, but also artifacts and ideas. He regarded a complex view of mobility as opening a new perspective on change in modern societies. However, in the wake of the turbulent war and revolution ridden period the accent of mobility studies shifted, the rise of an industrial society placed emphasis on the study of workplace change and inter-class transition. Urbanization stressed geographical mobility from village to city. These ideas became central for many empirical studies, viewing modern society as a space of inter-class transition, primarily transitions into the growing middle class. The new hegemonic project led to a new emphasis on the reproduction and expansion of the middle class. The middle class society became a model for many developing countries. The ideology of mobility that inspired their many reformers and revolutionary leaders in the third world who often strove to adopt a policy of mobility at all costs. The policy led to serious complications, discord of social positions, tensions, political tension including as a result of the inability of the young reformist regimes to solve the problem of structural weaknesses of developing countries. The ideology and practice of mobility met with problems of inter-class barriers and their limited permeability as well as with the problem of culture that appeared to be less flexible than social positions. It is fair to assume that many of the negative phenomena in the Arab countries or other less fortunate parts of the world are the outcome of the failed mobility projects, dashed hopes of prosperity and better life for the masses. In early 21st century it is appropriate to discuss new tacks of mobility theory, marking a return to a multiple approach to mobility that would equally take into account its structural and subjective aspects, compare societal and individual perceptions of success, relate workplace stability, geographical, housing and other dimensions that make modern society so fluid.