The 1966 Coleman Report, an investigation into educational opportunity commissioned by the U.S. Commissioner of Education, was released on the Fourth of July in what one reflection called “a vain attempt to avoid publicity.” Publicity was undesirable because James Coleman and his colleagues had found that educationally disadvantaged children in the U.S. were not as much the victims of poor schools as poor family backgrounds. Not only would it have been more politically correct to blame school systems than to blame the victim, but policy solutions would have been easier, too: it is easier to fund schools than to erase the effects of social inequality. No one could blame Coleman for trying to hide from the spotlight when releasing research showing that family background— factors like parents’ education levels and income—mattered far more than school quality in determining educational success.

The attempt was in fact vain. Not only did the Coleman Report attract much attention in the U.S., but it helped spawn similar research in other countries on how much school mattered relative to family background. Stephen Heyneman’s work on Uganda, dubbed “A Coleman Report for a developing country,” showed what Coleman had hoped to find for the U.S.—that schools could help reduce social inequality. Subsequent work showed that the U.S. was far from unique in its failure to produce equal outcomes for students from different backgrounds: family socioeconomic status influenced student outcomes far more in richer countries, while schools mattered more in poorer countries.

But what about the educational disadvantage associated with single parenthood? Is it smaller in poor countries than in rich countries? It is well-known that as a group, children in intact two-parent households do better in school than other groups in the United States and Europe. It is also known that among richer countries, as national income levels increase, so does the educational advantage to children in intact two-parent households. But until recently, cross-national comparisons of the effect of family structure on children’s education were limited to richer countries, e.g., those participating in international standardized testing like the Trends in International Mathematics and Science Study or the Program in International Student Assessment. So evidence on how children’s living arrangements affected their schooling in poorer countries was scattered and piecemeal.

We took up this question across a broad range of poorer countries for the 2013 World Family Map Report using data on whether children beyond primary-school ages were enrolled in school and whether they were behind the expected grade level for their age. Good educational outcomes include much more than being enrolled in the proper grade, but measuring education this way allowed us to employ standardized demographic surveys to understand how family structure affects education in poorer countries. In the initial analysis, children living with only one biological parent sometimes shared the educational disadvantage commonly found in richer countries—but there were also plenty of countries where educational outcomes didn’t depend on family structure, plus a few where children living with only one biological parent did better than children living with both biological parents.

It turned out that children living with only one biological parent did better in school if their mother was still in union with their father. That is, the apparent advantage to living with one biological parent in some countries generally did not apply to children in single-parent families, nor to children in stepfamilies. Only intact unions that were not coresident—probably ones where the father was a labor migrant, sending money home to boost the family’s income—offered educational advantages.

National income significantly conditions the effect of single motherhood.

We also extended this line of work with a focus on Latin America and the Caribbean—a region where national income levels vary quite a bit. Some of our findings did not depend on national income level, e.g., mothers being absent from the home was associated with poorer educational outcomes everywhere, and children in stepfamilies were also at a fairly consistent disadvantage.

But children of single mothers were disadvantaged only in the richest countries of Latin America and the Caribbean. Multilevel analysis confirmed that national income significantly conditioned the effect of single motherhood. In other words, it seems like the effects of single motherhood work much the same way as low family socioeconomic status does: it is not such a big deal in poor countries, but in richer countries family-level factors matter more.

This is bad news for a region where most countries have higher rates of out-of-wedlock childbearing than anywhere in Europe (including Sweden). It means that patterns of family formation and dissolution in Latin America and the Caribbean already present obstacles to educational progress, and that further economic development will only make children’s living arrangements more important for their success. Our work supported the unpalatable implication of the Coleman Report that expansion of public resources cannot equalize outcomes for children of different backgrounds.

Why not? We cannot answer that question with the standardized demographic surveys we used in our research, but we can come up with some probable explanations. Consider a country like Guatemala, where less than 40 percent of age-eligible children are enrolled in middle school. The children continuing past primary school are surely from better-off families, but it is also the case that school continuation in poor countries depends on interest and aptitude: parents are more likely to make the sacrifices necessary to keep a child in school if that child is bright. That means that in places like Guatemala, where school is not universal, the kids that go to school are the least likely to need help making it through. In that case, time resources in the family might not matter much, meaning family structure would not be strongly related to students’ achievement. Then as a country grows wealthier and schooling becomes more common, less promising children become more likely to attend. This is good—a child who does not show early promise may flourish in school, and even those who never flourish in school can benefit from it.

Two parents have more time to prevent at-risk children from falling through the cracks.

That is what I am hoping for, praying for, and working toward for my daughter. My husband and I sometimes spend over an hour helping her complete a worksheet of four first-grade math story problems. She’s getting resource support at school in both math and reading. (In other words, I don’t spend this kind of time because I’m obsessive or over-involved: it takes this long because even after the problems are read to her, she still needs help figuring out what to do.) If I were a single mother, I would probably work full-time instead of part-time, and sometimes grocery shopping might trump homework because there wouldn’t be another parent helping keep the kitchen stocked. Children of single parents are not doomed to failure—when 40 percent of kids go to middle school, they are part of the mix. But two parents have more time to prevent at-risk children from falling through the cracks, and in richer countries, where close to 100 percent of kids go to middle school, at-risk children—whose achievement is strongly dependent on their parents’ help—make up a larger share of students. This may be one reason family structure appears to affect educational outcomes much more in rich countries, where almost all kids go to school, than in poor ones.

There is at least one more reason why the single-parent disadvantage would be greater in richer countries: it takes time to utilize many public resources to their full potential. Free museums don’t boost learning if no one has the time to take kids for a visit. Even Sesame Street boosted the skills of middle-class children who were more likely to watch with a parent more than it helped lower-class children who were more likely to watch alone. With all the demands that modern education places on students, it is no wonder that time resources in their families matter.