His speech to the 13,000 delegates came, however, as a battle over debt relief was building between developing and developed countries and as more heads of state announced they would not be attending.
President Bakili Muluzi of Malawi cancelled his visit, state radio declaring that the £120,000 cost of a national delegation from one of Africa's 10 poorest countries to a summit estimated to be costing the hosts Denmark alone about £20m, would have been "extravagant". Mexico, Brazil and Venezuela said their heads of state will not be there.
Mr Boutros-Ghali said a new social contract was required "at the global level" to "bring hope to states and to nations, and to men and women around the world. That should be the focus of this world summit."
With the gap between rich and poor having doubled since 1960, social development was the key to maintaining peace, he said. "We know today most of the armed conflicts with which the United Nations organisation is faced are domestic conflicts ... most have evident social and economic causes. We must state again the clear link between the promotion of development and the preservation of peace."
He added that the UN's job was "to prevent the fatigue of public opinion and member states. The alternative, indifference, is more dangerous."
Developing countries in the Group of 77 presented a radical list of demands, including cancellation of Third World debt, increased aid, and the creation of a new International Bank for Social Development.
But one of the summit's many difficulties is that decisions on debt are primarily decided elsewhere - in the International Monetary Fund, World Bank and G7 forums. Industrialised countries have already indicated that while debt issues will be discussed, hard decisions are not expected in Copenhagen.
Cielito Habito, Group of 77 chairman, said more meaningful steps towards debt reduction were needed, and a fund was required to ensure summit adopted measures were followed.
Areas of potential conflict as the summit works towards a final declaration include workers' rights, where less developed countries may argue those cannot be afforded, the 20/20 proposal for 20 per cent of aid and national budgets to be devoted to social development, and the debt issue.
Despite the scepticism, Juan Somavia, the Chilean UN ambassador who conceived the summit, said it marked the "the formal end of the Cold War".
John Major's decision not to attend was not surprising. "There is an attitude that you don't discuss international social issues," he told BBC radio.
The world must "draw on the extraordinary capacity for mobilisation of non-governmental organisations and the potential for integration offered by private enterprise and investors". Concerted action was needed, but states remain "primarily responsible" for setting social policies in motion, he added.