The United Nations has before it a recommendation from a high-level panel on U.N. reform to create a new international agency for women. We have not seen such an opportunity before, not in the United Nations’ 62 years.

It can safely be said that the struggle for gender equality is the single most important struggle on the planet. And, if a women’s agency is supported vigorously by the new secretary-general (for many of us, the decisive test of his tenure), passed by the General Assembly, and supported by women’s groups around the world, we may finally have in place a formidable entity to help change the lives of women everywhere.

The new agency would be led by an under secretary-general, chosen on an unrestricted global basis, and must have at least a billion dollars annually to begin with, plus the mandate to institute targeted programming for women on the ground. It must also be staffed by experts on women’s issues, rather than the motley compendium of generalists within many of the existing U.N. agencies who now merely pretend to drive the gender agenda.

International Women’s Day—March 8—was filled with cries of anguish and calls for action at the United Nations. Statement after statement by luminaries in the U.N. community called attention to the welter of injustices visited upon women, from nightmare levels of maternal mortality, to terrifying data on sexual violence, to the harrowing vulnerability of women and girls in the face of the HIV/AIDS pandemic. Every speech acknowledged some incremental progress, but emphasized that there was still a long, long way to go.

That path will undoubtedly be shorter if we get the women’s agency. For too many women, the world has been fatally decimated by poverty, disease, and conflict, all of it sustained by staggering male indifference. A women’s...