The Queen has addressed the United Nations for the first time in more than 50 years.
In her historic speech on Tuesday she said she has "witnessed great change, much of it for the better" since the first time she stood before the organisation, and praised their achievements as "remarkable".
But she also recognised that, despite their efforts, "so much remains to be done," particularly in the struggle against terrorism and the response to climate change.
In the seven-minute address, the monarch called for special attention to the "risks facing smaller, more vulnerable nations," many of which belong to the 54-member Commonwealth of Nations of which she is head.
"I know of no single formula for success," said the 84-year-old royal.
"But over the years I have observed that some attributes of leadership are universal and are often about finding ways of encouraging people to combine their efforts, their talents, their insights, their enthusiasm and their inspiration to work together."
The Queen made the comments during the General Assembly of the United Nations in New York.