Data on the educational attainments and occupational statuses of all siblings from 1653 West German families, from three cohorts born respectively around 1930, 1940, and 1950, are analyzed in order to estimate effects of measured (father's and mother's schooling, father's occupation, and number of siblings) and unmeasured family background factors. The analysis shows that there are unmeasured family factors which influence schooling and occupational status. Further, we find some evidence of trends in family effects on schooling over cohorts in West Germany, in that the effect of father's occupational status is decreasing, and no different family effects for males and females. Analyses on cross- and like-sex siblings pairs do not lead to divergent results. Including controls for measurement error we find no evidence for a family bias in the effect of schooling on occupational status in West Germany. © 1992.