Ten surveys of American men aged 25-64 were analyzed to determine the effects of family background, adolescent personality traits, cognitive test scores, and years of schooling on occupational status and earnings in maturity. Some of the findings follow: Data on brothers indicated that prior research has underestimated the effect of family background on earnings. Adolescent test scores indicated that cognitive skills have a substantial effect on occupational status and earnings independent of background. Data on adolescent behavior indicated that personality traits may exert as much impact on economic success as cognitive skills. Controlling background and adolescent test scores indicated that less than half the observed association between years of schooling and earnings is causal. (The last third of this report covers the study's methodology. It examines the measures used regarding economic success, family background, test scores and years of schooling; describes the statistical methods; and pinpoints the reasons for differences between the nine principal samples. An appendix describing the samples used in this study is available as a separate document.) (EM)