The hypothesis that the Scholastic Aptitude Test (SAT) score decline is a result of changing American family sizes and configurations is explored. This possible explanation of declining SAT scores had been offered by Robert B. Zajonc in an article discussing the relation between family configuration and cognitive development. Since a number of investigations have shown that "earlyborn" students--those who were the first or second child in their families--and members of small families tend to have higher scores on tests such as the SAT, a change in the representation of students who are earlyborn and members of small families in the population could possibly cause a decline in the average for the total population. The confluence model hypothesis is explored through a consideration of the magnitude of the change in family configurations over the years of interest, and the magnitude of observed score difference for the SAT. It is concluded that, while the Zajonc hypothesis seems sound, it could only account for a small portion of the total SAT score decline. (Author/EVH)