President Barack Obama and leaders from 19 other major nations began arriving Friday in Toronto, Canada for this weekend's G-20 and G-8 summits.
One of the main goals of the conferences is to develop ways to keep the global economy from slipping back into a recession.
Before departing the White House Friday, the president expressed the hope that he could build upon the success of the two previous G-20 gatherings "by coordinating our efforts to promote economic growth, to pursue financial reform, and to strengthen the global economy" in the wake of financial crisis.
"This crisis proved, and events continue to affirm, that our national economies are inextricably linked," Obama told reporters gathered on the White House South Lawn. "And just as economic turmoil in one place can quickly spread to another, safeguards in each of our nations can help protect all nations."
Significant decisions will also be made on how to control ballooning deficits.
Meanwhile, security surrounding the summits has been tight.
On Thursday, police arrested a man in downtown Toronto who was carrying weapons and gasoline in his car a block away from where the world leaders will meet. Authorities said the incident was not connected to the summits.