This review deals mainly with British studies and is focused on choice of scientific and technological occupations. Two basic influences on occupational choice are discussed: (1) the acquisition and development of the individual's personal traits, and (2) his environment--school, family, economic and social position. Evidence indicates that children from different social groups have unequal opportunity of gaining admission to a grammar school, of successfully completing a grammar school course, and of starting a course of higher education. An American study suggests that differential opportunity may remain even under a battery of controls. The full effect of these processes on the recruitment of scientists and technologists has not been systematically investigated. (CH)