The report by the United Nations Educational, Scientific and Cultural Organization, or UNESCO, outlines a vicious circle. Rising poverty and malnutrition - one of the spinoffs of the global economic crisis - has prevented many children from attending school. But that's only part of the problem, says Samer Al-Samarrai, one of the study's authors.
"Even when they're in school, their ability to concentrate and actively participate in lessons - the financial crisis has had a really big impact on that," said Samer Al-Samarrai. "But second of all, the crisis has really put national education budgets under substantial pressure."
The United Nations says 72 million children do not attend school. Universal primary education by 2015 only five years from now - is one of the U.N.'s Millennium Development Goals.
During the past decade, progress has been made. About 33 million more children now attend school than in 1999. And many more children now complete primary school.
Some of the biggest successes have been in Sub-Saharan Africa. But the region's children might be among the most affected by the economic downturn.
Ultimately, says education economist Samer Al-Samarrai, everyone stands to lose.
"If levels of aid to education drop, this is likely to set back progress for a whole generation of children," he said. "And education is an investment in the future."
The UNESCO report says international aid for education needs to be reformed. It calls for donors to commit billions more dollars in education aid to meet the U.N. goal of education-for-all. The report also urges the United Nations to host a donors' conference this year to address the education financing shortfall.