has risen dramatically
in the last 30–40 years,
making the gap in income
and low-income families
gap is large when children enter kindergarten—and does not
grow substantially during the school years—suggests that
the primary cause of the gap is not unequal school quality.
In fact, the data in Figure 2 show that schools may actually
narrow academic achievement gaps, rather than widen them.
The data show the gap narrowing between the fall and spring
of the kindergarten and 1st grade years—periods when students were in school—and widening in the summer between
kindergarten and 1st grade—when they were not in school.
Although we can’t assume that the same pattern holds in later
grades, the ECLS-K data do suggest that schools may reduce
© OLEGDOROSHIN/SHUTTERS TOCK
inequality rather than widen it. This finding is consistent with
other research on the “summer setback” that has been conducted in smaller, more localized samples (for example, see
Alexander, Entwisle, & Olson, 2007).
Why Has the Income Achievement Gap Grown?
To understand the reasons for the growing income
achievement gap, it is necessary to look at the social history
of the past 50 years in the United States. A few key trends are
First, income inequality has risen dramatically in the last
30–40 years, making the gap in income between high-income
and low-income families much greater. In 1970, a family
with school-age children at the 90th percentile of the family
income distribution earned 5 times as much as a family at
the 10th percentile; today, the high-income family earns 11
times more than the low-income family. 2 This rapid growth in
income inequality means that high-income families now have
far more resources, relative to low-income families, to invest
in their children’s development and schooling.
Second, upward social mobility has become far more difficult and far less certain than it was 50 years ago, partly
because of rising income inequality and partly because of
declining economic growth. While the economy was growing
rapidly in the 1950s and 1960s, the vast majority of children
in the United States (particularly white children) grew up in
families in which they were much more economically secure
than their parents (most of whom had grown up during the