The study, published in the journal Education Next, estimates the relationship between adolescents’ family situations and their future educational attainment, and finds that the education gap between young adults who lived in single-parent families and those who lived in two-parent families widened substantially between 1968 and 2009.

The number of single-parent households in the US has increased markedly over the past 50 years. In 1965, Assistant Secretary of Labor Daniel Patrick Moynihan published a report that found that 51 percent of low-income children entering adolescence were living in single-parent households. Over the next three decades, this figure jumped to 75 percent.

Using data from the US Department of Labor’s Panel Study of Income Dynamics, the researchers tracked the educational and economic life cycle of families and their children who were teens between 1968 and 1999. While the number years of school completed increased over time for children of both single- and two-parent families, teens from single-family homes received fewer years of schooling throughout the time period. The gap between the two groups widened from 0.63 years for those who were age 24 in 1978 to 1.32 years for those who were age 24 in 2009, with the widening accelerating in the 1990s.

“The negative relationship between living with a single parent and educational attainment has grown since the time Moynihan’s report was published, which is troubling,” said Kathleen M. Ziol-Guest, research associate professor in the Department of Humanities and Social Sciences at NYU’s Steinhardt School of Culture, Education, and Human Development and one of the study’s authors.

“In other words, American children raised in single-parent homes appear to be at a greater disadvantage educationally than ever before.”

The data also reveal a disparity in college graduation rates. During the 1980s, the likelihood of graduating from college was 8 percentage points less among those who had lived in single-parent families than their peers with two-parent families. In the 11-year period ending in 2009, that gap more than doubled to 17 percentage points.

When the researchers adjusted their analyses for family income to see whether income was responsible for the differences between single- and two-parent families, they found that income accounted for about half of the education disadvantage facing students from single-parent families.

Other factors affecting educational attainment include mother’s age, mother’s education, and number of siblings. Mother’s education remains the most important factor associated with the number of years a child remains in school, and the age of the mother grew increasingly important during the period studied.

“While many factors contribute to gaps in educational attainment, our findings suggest that being raised by a two-parent household has become increasingly important since Moynihan’s report,” Ziol-Guest said.