Today we celebrate International Day of the Girl and the strength of girls everywhere.

Girls are one of the most powerful forces for change in the world: When their rights are recognized, their needs are met, and their voices are heard, they drive positive change in their families, their communities, and the world.

Millions of girls face hardship and discrimination, but they refuse to stay quiet and let the status quo continue. International Day of the Girl is a reminder that we must stand with them and promote the rights and well-being of girls everywhere. It’s the right thing to do – and it’s the absolutely necessary thing to do to end poverty, promote prosperity, and build a more just and peaceful world.

For too long, girls have been ignored in the global agenda. The United Nations Foundation and its Girl Up campaign are working with the United Nations, partners, and girls themselves to change this.

Together we can take action for girls today through innovative initiatives like Girl Up’s ‘11 Days of Action.’ At the same time, we need to secure a place for girls in the global development agenda. To make sure girls are not left behind, the Nike Foundation, the UN Foundation, and many other partners joined with girls around the world to launch the Girl Declaration, a call to action to make girls are a priority in the post-2015 development agenda.

I’m constantly inspired by the passion and potential of the girls I meet. Our obligation and our opportunity today is to empower girls everywhere to change the world. Our support for girls needs to be immediate and sustained in the coming years and decades.  This is what girls deserve, and it’s what our world needs.