The article talks about how people and groups can help make communities better by promoting smart growth. Smart growth means designing transportation systems that focus on biking, walking, and public transit, while also mixing different types of buildings to protect the environment and create stronger communities. These "smart growth catalysts" work together to push for smart growth projects in their areas. They team up with local, state, and regional groups to make these ideas a reality. By working together, they can improve how cities are designed, create new transportation options, and help the environment. The article gives examples of how these catalysts have already made positive changes in their communities.