The leaders of the Group of Eight leading industrialised nations and Russia are gathering in Gleneagles, Scotland, for what is widely regarded as one of the most important G8 summits in recent years.
BBC News profiles the presidents and prime ministers who will drive events at the meeting.
TONY BLAIR: UK PRIME MINISTER
As host of the summit, Mr Blair is determined to promote debt cancellation and aid to Africa, as well as agreement among fellow G8 nations on measures to tackle climate change.
However, his closest ally, US President George W Bush, has already indicated he will not back climate change initiatives if he considers them a threat to the US economy. Meanwhile, Mr Blair's frosty relationship with France's President Chirac could be further tested following London's success over Paris in the bid to host the 2012 Olympic games.
PAUL MARTIN: CANADIAN PRIME MINISTER
Canada's Liberal leader is struggling at home, with a sponsorship scandal involving kickbacks to previous Liberal administrations weighing on his minority government.
Mr Martin could push for expansion of the G8 to include China, Brazil and India. He is also keen to commit Canada to giving 0.7% of its GDP in foreign aid.
JACQUES CHIRAC: FRENCH PRESIDENT
The longest-serving national leader at the G8 table, Mr Chirac has suffered at home recently with France's rejection of the European Constitution and Paris' failure to win the bid to host the 2012 Olympic Games.
He is keen to promote a French plan to impose a levy on airlines to finance overseas development.
GERHARD SCHROEDER: GERMAN CHANCELLOR
Another G8 leader who may be happy to leave his troubles at home, Mr Schroeder is expected to face a national election later this year after his Social Democrat-led coalition deliberately lost a parliamentary vote of confidence last week.
Keen to secure his alliances with the French and Russian presidents, Mr Schroeder is wary of dramatically increasing aid across Africa until more effective government institutions are put in place.
SILVIO BERLUSCONI: ITALIAN PRIME MINISTER
An ally of Mr Blair and Mr Brown, Mr Berlusconi is keen to improve his standing as an international statesman as Italy's economy struggles with recession.
He is likely to support Britain's proposals on aid to Africa and climate change, but, like Germany, is wary of the financial costs Rome will have to incur.
JUNICHIRO KOIZUMI: JAPANESE PRIME MINISTER
Japan's leader since 2001, Mr Koizumi has pushed for far-reaching reforms of his country's stagnant economy, the world's second biggest after the US.
Mr Koizumi could offer the UK support over climate change and is thought to be considering increasing Japan's aid to Africa.
VLADIMIR PUTIN: RUSSIAN PRESIDENT
Keen to preserve Russia's standing on the international stage, Mr Putin is battling to preserve foreign business confidence in his country following the government's successful campaign against former oil giant Yukos.
Given its own economic worries, Russia is unlikely to pledge big increases in aid to Africa. However, Moscow recently backed the Kyoto Accord on climate change.
GEORGE W BUSH: US PRESIDENT
Indisputably the biggest player at the G8 table, Mr Bush has warned friends and critics alike that the US will not back any deal on climate change which could have a negative effect on the US economy.
On aid to Africa, Mr Bush could be more amenable - although the US will have to go some way to achieving the UN goal of spending 0.7% of GDP on overseas aid.