Decades ago, donors saw aid as a transfer of resources from rich to poor countries. Today they see it more as a means of improving recipient countries' use of domestic resources. And though aid has had its successes in humanitarian relief and family planning, its record is mixed when it comes to promoting economic growth. Many nations in sub-Saharan Africa are poorer than when they began receiving aid. The solution is not to end foreign aid, but for donors to know when to say when, cutting off countries that fail to adopt sound economic policies and rewarding those that do.