An eight-equation model embodies the hypothesis that cultural differences among ethnic-religious groups give rise to differences in psychological dispositions, which, though not directly observable, influence occupational achievement, directly or via educational attainment, while being subject to feedback from one or the other of these endogenous variables. Dispositions are reflected in three fallible indicators, constructed from items in a survey interview of native white men in the Detroit area; the survey also secured socioeconomic measures and an estimate of intelligence. The model is block recursive and over-identified. Parameter estimates are secured by a sequence of ordinary least squares and two-stage least squares procedures, after solving out the structural equations to eliminate the unobservable variables. Numerical results do not strongly support the 'Protestant Ethic" theory of achievement, but do suggest that the influence of education on occupation is mediated by motivational as well as cognitive and institutional factors.