The birth order factor: ordinal position, social strata, and educational achievement.

The relationship between birth order and academic attainment of 817 men and women from a variety of socioeconomic backgrounds in the United States was explored. A measure of respondents' family economic situation during their growing-up years was incorporated. Birth order was found to have an impact on total years of education completed among members of the middle class. The observed patterns also indicate that "only" children, contrary to findings of previous research, appear disproportionately to excel in terms of educational attainment. These findings support a resource-dilution hypothesis.