As many as 200,000 people -- many wearing white -- formed a human chain around Scotland's medieval capital of Edinburgh, pressing for action against African poverty at the upcoming Group of Eight summit at the nearby Gleneagles resort.
Edinburgh's "Make Poverty History" demonstration coincided with Live Eight rock concerts being held around the world.
Britain's Chancellor of the Exchequer, Gordon Brown, said on Saturday that those standing up for Africans living in poverty are engaged in a great moral crusade.
The demonstrators want industrial nations to cancel African debt, increase aid to poor nations, and remove trade barriers blocking the import of African products.
Leaders of the world's seven principal industrial countries (Britain, Canada, France, Germany, Italy, Japan and the United States) and Russia begin their summit Wednesday.