Just over the border in Lausanne, Swiss police dispersed thousands of demonstrators, while outside Evian, French riot police used tear gas on protesters.
Demonstrators blocked traffic for hours on bridges and highways around Geneva, across the lake from the meeting. Swiss police officials estimated the crowd at 50,000; protest organizers said it numbered 120,000.
Inside the summit, world leaders are having a "rapprochement" of sorts: Trying to rebuild relations between countries that disagreed over the war in Iraq.
President Bush took the first step by reaching out to France, reports CBS News Correspondent John Roberts.
The meeting's most closely watched moment was the welcoming handshake between French President Jacques Chirac and U.S. President George W. Bush, whose wartime differences led to angry recriminations on both sides of the Atlantic. They greeted each other with polite smiles, a brief handshake and small talk before walking into a luncheon with other presidents and prime ministers.
This was the handshake the world was waiting to see, a clear sign that the two leaders want to put Iraq behind them and move on.
It wasn't the warmest of welcomes - just enough to suggest the long frost in US-European relations may begin to melt under the hot Evian sun.
If Bush hopes to forge strong partnerships in the war on terror, rebuilding Iraq, and kick starting the global economy, he can't afford to personalize international politics, says former NATO ambassador Robert Hunter.
"You've got to swallow hard and say okay, I don't like what Chirac did, I don't like what Schroeder did, I don't even like Putin! But let's get beyond it and put the smiles on because we need one another for the future," says Hunter.
This is Bush's first opportunity to meet many leaders like Chirac, German Chancellor Gerhard Schroeder and Chinese President Hu Jintao since the war.
At a pre-summit meeting with Vladimir Putin, both declared the relationship was tested by Iraq and survived.
"Strange as it may sound," Putin said, the United States and Russia have even strengthened ties -- a point that Bush was happy to echo.
"We will show the world that friends can disagree, move beyond disagreement and work in a very constructive and important way to maintain the peace," said Bush. "This experience will make our relations stronger - not weaker…."
Improved relations will take time. President Bush has already earned high marks for his $15 billion initiative to combat AIDS in Africa. But Europe remains skeptical of his basic reasons for the war - and is anxious for more evidence of a banned weapons program than the suspected bioweapons labs he cited as proof today.
The president will also take the extraordinary step of leaving the G8 early. Mr. Bush will host his first-ever Mideast summit on Wednesday, a step he has carefully avoided until now. What might be seen as another snub was forgiven by European leaders who have always felt the only road to peace in the Middle East goes right through the Oval Office.
Many voices in the Administration still believe that the president's so-called "road map" to peace is doomed to failure. But they see little political risk in taking such a high profile position, because the problems seem so intractable, just making the effort will be seen as a positive.
The annual summit of industrialized nations brought together the leaders of the United States, Britain, France, Germany, Italy, Japan, Canada and Russia at a spa on the banks of Lake Geneva. They were joined on the opening day by leaders from Saudi Arabia, Egypt, Africa and developing countries such as China, India and Mexico -- a move intended in part to answer the criticism of anti-globalization protesters that the G-8 was a rich country's club insensitive to the needs of poorer nations.