If couples decide to have fewer children in order to achieve higher “quality” offspring, are they correct in assuming that the quality of children bears an important and inverse relation to family size? If they are correct, how does number of children operate to affect individual quality? This research (using U.S. whites primarily) takes educational attainment (among adults) and college plans (among youngsters) as the principal indicators of quality, but also directs some attention to measures of intelligence. The analysis supports the “dilution model” (on average, the more children the lower the quality of each child) and indicates that only children do not suffer from lack of siblings, and that other last-borns are not handicapped by a “teaching deficit.” Number of siblings (relative to other background variables) is found to have an important detrimental impact on child quality—an impact compounded by the fact that, when couples are at a stage in life to make family-size decisions, most background factors (however important to the quality of their children) are no longer readily manipulable. A special path analysis of college plans among boys uses a modification of Sewell’s Wisconsin Model as its base. The results show that number of siblings is a negative influence on intervening variables affecting college plans. In general, the research documents the unfavorable consequences for individual siblings of high fertility, even in a country that is (at least for whites) as socially, economically, and politically advantaged as the United States.