used to measure occupational mobility are not fixed for long periods of time. Second, good statistics are not available. Third, the meaning of occupational moves differs at each historical period. Fourth, good measures of occupational mobility are hard to obtain and disagreements usually arise over their interpretation. And we should add that occupational structures themselves change and take on a different meaning at different stages of economic and industrial development.
A long-established ideal of equality of opportunity is an integral part of the American culture pattern. Our children are early imbued with the faith that regardless of the humility of their beginnings, no doors of opportunity are closed to them--hard work and talent, the expectation is, will be rewarded. The doctrine is by no means unchallenged, but recent public opinion study has demonstrated that, by and large, most American adults still cling to it. Most believe that one man's opportunities to succeed are as good as another's.1
Though doubtless the belief is supported by a substantial amount of socioeconomic mobility as it can be observed by the citizen in the not too infrequent phenomenon of his children or those of his neighbors bettering themselves in economic pursuits, just how much of such mobility exists is not a question that at present can be answered with any great confidence by the social scientist. Research, though its need has frequently been recognized, has failed somehow to be carried out on the large scale and in the requisite detail the problem demands. As long ago as 1927 Sorokin gave emphasis to the importance of such study and reviewed the then existing research on vertical occupational mobility.2 Such research had characteristically been based upon small samples typifying only segments of the occupational order and had varied from one study to another in respect to definition and measurement of the relevant variables, and Sorokin did not fail to recognize the essential crudeness of the indices of occupational continuity and to point up the need for further exploration. Several investigations have subsequently