Women in the developing world have made strides in education, but still lag far behind men in opportunities, a gender gap that is hampering growth, the World Bank said in a report.
Calling on countries to work to shrink that gap, the World Bank said gender equality is important in its own right as well as being "smart economics."
"Countries that create better opportunities and conditions for women and girls can raise productivity, improve outcomes for children, make institutions more representative, and advance development prospects for all," the report said.
According to "World Development Report 2012: Gender Equality and Development," the disparities between boys and girls in primary education have almost closed over the past 25 years, and at the secondary level, the gaps are shrinking rapidly.
But in many areas, girls and women continue to suffer discrimination that keeps them second-class citizens economically and socially, and even in health.
The World Bank said the worst disparity was in the mortality rate relative to men in developing countries.
"Globally, excess female mortality after birth and 'missing' girls at birth account for an estimated 3.9 million women each year in low- and middle-income countries."
The Bank said about two fifths "are never born due to a preference for sons," while a sixth die in early childhood and more than a third die in the child-bearing years.
Those losses are mounting in Sub-Saharan Africa, especially in countries severely impacted by HIV/AIDS, it said.
"We need to achieve gender equality," said Robert Zoellick, the World Bank president.
The 187-nation development lender has provided $65 billion in the past five years to support girls' education, women's health, and women's access to credit, land, agricultural services, jobs and infrastructure, he said.
Zoellick said that while that work had been important, it had not been enough or central enough to the Bank's mission.
He pledged the bank would find "other ways to move the agenda forward to capture the full potential of half the world's population."
The Bank proposed four areas for action: addressing the excessive mortality rates and gender gaps in education, closing earning and productivity gaps, giving women greater voice within households and societies, and curbing the transmission of gender inequality from generation to generation.
The report detailed how girls now outnumber boys in secondary schools in 45 countries, and women outnumber men in universities in 60 countries.
Progress also has been made in life expectancy, where women in poor countries outlive men and live 20 years longer than they did in 1960.
But countries stand to gain by addressing the remaining disparities, the Bank argued.
As an example, Bank economists estimated that improving women's property rights in Burkina Faso would increase total household agricultural production by about six percent -- by simply reallocating resources such as fertilizer from men to women.
Eliminating barriers that block women from working in certain occupations would reduce the productivity gap between male and female workers and boost output per worker by 3.0 to 25 percent across a range of countries.
"Blocking women and girls from getting the skills and earnings to succeed in a globalized world is not only wrong, but also economically harmful," said Justin Lin, the World Bank's chief economist.