Check out the Environmental Youth Alliance (EYA)! EYA describes itself as “a local, youth driven non-profit organization dedicated to the health of our urban environment, our planet, and the well-being of its people.” Their mission? “[T]o inspire children, youth, and youth adults to connect with the natural world and become sustainability leaders in their communities.” They carry out their mission by organizing community activities that teach and build important skills about topics such as what sustainability issues are key to urban living.
Some of their programs include gardens and a community nursery and orchard. They have three ongoing projects, as well: Treehouse Treats, Lawns to Loaves, and GrassRoutes, which involves biking all the way across Canada! Check out the Programs and Projects page to learn more!
If you do not live in Canada, then check out EYA International! There is a whole website dedicated to overseas projects run by EYA, including the Slum Film Festival, which showcases films about slums, and Up With Hope, a community project in Nairobi, Kenya. Check out the project page to learn more.