The juxtaposition of themes—social mobility and economic development—in the title of the conference may invite acceptance of an unwarranted assumption. In point of fact there is and can be no fixed and determinate general relationship between measures of economic growth and indexes of social mobility, either over time in one country or between countries at a point in time. A whole set of auxiliary postulates, each empirically contingent, must be adopted before a relation between mobility and growth can be deduced.