At the dawn of the new millennium, world leaders pledged to tackle poverty, disease, ignorance and inequality — and went beyond generalities to commit themselves to specific goals. Progress has been made over the past decade, but many countries are still struggling to meet the 2015 target. On Monday, another summit will open in New York to review what has, and hasn't, been done. "These Millennium Development Goals are a promise of world leaders," says Secretary-General Ban Ki-moon, who invited leaders of the 192 U.N. member nations to the three-day summit. Read more.