Data on the problem of the loss of professional manpower by developing countries to develop countries is reported and analyzed from a survey of over 1,300 foreign students in over 30 U. S. colleges and universities. The ideological and scholarly debate generated by the brain drain and approaches to the study of professional migration are reviewed, and a sociological model of student nonreturn is presented. The sampling and field work procedures for gathering the data utilized for identifying a pattern of student nonreturn in the U. S. are described. Factors considered as operating in responses to student nonreturn include characteristics of the students' countries, opportunities for work and education, social group influences, and motivational states. These factors are seen as operating at two time periods: the period before arrival and the period of study in the U. S. Discussion focuses on social group effects on nonreturn as well as objective opportunities and their perception by students within these two time periods. In the last chapters, multivariate regression models are proposed and analyzed. Finally, some of the policies that have been suggested to deal with the brain drain are discussed and evaluated in the light of the survey findings and analysis. (KSM)