The word is spreading: investing in girls is the catalyst poor countries need to break the cycle of poverty. The second half of the message often gets short shrift: gender equality benefits everyone -- girls, women, men, boys.

In the past few years, "the girl effect" has been explored by business and political leaders at the World Economic Forum in Davos and the G8 Summit here in Canada. Proponents of investing in girls' education in developing countries include such influential figures as Senator Hillary Clinton, Oprah and Robert Zoellick, president of the World Bank. Zoellick has said that investing in girls is not only fair, it is a smart economic move.

I've engaged on this topic with groups ranging from the Economic Club of Canada to secondary school students to supporters of fundraising parties at fashionable stores. I've followed the excited chatter on Facebook and Twitter as young Canadian girls discover their power to contribute to expanding opportunities for their peers in poorer countries.

But I'm well aware as I do so of an underlying tension. What about the boys? In our focus on girls, are we leaving the boys behind -- making them the new disadvantaged group?

Truth is, the gender equality so many of us are working to achieve for girls in developing countries is good for boys too. Healthy, educated mothers have healthier children. They know how to provide proper nourishment and intellectual stimulation in the all-important early years of a child's development. They can use their skills to earn income, which they generally invest in their families' welfare. All their children -- girls and boys -- enjoy a better start to life.

Every member of a family benefits from the breaking down of gender stereotypes and role definitions that constrain personal choice. The world over, boys are conditioned to keep emotions bottled up and take set-backs "like a man." Wherever you stand on the thorny issue of how much so-called "male behaviour" is hard-wired versus learned, it can only be a good thing to teach boys emotional outlets other than aggression and violence.

The flip side for a boy of being chosen over his sisters as the one to get an education is the underlying assumption that it will be up to you to provide financial security for your family. That can be a terrifying prospect for any boy or man, particularly so in countries with weak economies. Societal norms aside, many secretly long for a spousal partnership in which both individuals are allowed to contribute to family life according to their gifts and interests, rather than rigid gender roles.

I certainly do not underestimate the challenge of making gender equality a global reality. It will require concerted action to change how children are educated, from their earliest days through their formal schooling. It will require public awareness campaigns that get people talking openly about uncomfortable issues. And it will require new laws.

Any approach to seeking gender equality that paints all men and boys with a broad brush as the "problem" rather than as partners in bringing about and benefitting from solutions is misguided and will eventually backfire. As a general rule, men still hold greater power than women in political, economic and familial circles. For that reason alone, they must be part of the solution.

It takes tremendous courage for a boy or a man to be the first in his circle to challenge stereotypes and act according to his own conviction that all humans share the same rights. In my work, I've seen so many stand up and do this -- from national and community leaders to very small boys. I've heard husbands say that doing housework with their wives has given them wonderful opportunities to share dreams and plans for their families. Fathers delight in time spent talking with their sons and daughters about their studies and their friends in cultures where "we only used to work." Over time, the actions of these agents of change will create new social norms.

It's not a zero-sum game, an either-or proposition. Investing in gender equality can benefit all.

Rosemary McCarney is CEO of Plan Canada, which has just released their fifth annual report on the state of the world's girls, this year titled "So what about boys?"