The Earth Summit (in Portuguese: Eco '92) is the informal and best-known name for the United Nations Conference on Environment and Development (UNCED).
The Earth Summit, held in Rio de Janeiro from June 3 to June 14, 1992, was unprecedented for a United Nations conference, in terms of both its size and the scope of its concerns.
One hundred and seventy two governments participated with one hundred and eight at level of heads of State or Government. Some 2,400 representatives of non-governmental organizations (NGOs) attended, with 17,000 people at the parallel NGO Forum, who had so-called Consultative Status.
The issues addressed included:
- systematic scrutiny of patterns of production — particularly the production of toxic components, such as lead in gasoline, or poisonous waste
- alternative sources of energy to replace the use of fossil fuels which are linked to global climate change
- new reliance on public transportation systems in order to reduce vehicle emissions, congestion in cities and the health problems caused by polluted air and smog
- the growing scarcity of water
An important achievement was an agreement on the Climate Change Convention which in turn led to the Kyoto Protocol. Another was agreement to "not carry out any activities on the lands of indigenous peoples that would cause environmental degradation or that would be culturally inappropriate".
The Convention on Biological Diversity was opened for signature at the Earth Summit, and made a start towards redefinition of money supply measures that did not inherently encourage destruction of natural ecoregions and so-called uneconomic growth.
The Earth Summit resulted in the following documents:
In addition to the official documents at the Earth Summit, a set of NGO Alternative Treaties were developed under the auspices of the International NGO Forum. 
Further development and implementation these issues was undertaken by various entities within the UN:
At its close, Maurice Strong, the Conference Secretary-General, called the Summit a "historic moment for humanity". Although Agenda 21 had been weakened by compromise and negotiation, he said, it was still the most comprehensive and, if implemented, effective programme of action ever sanctioned by the international community.
The Earth Summit influenced subsequent UN conferences, which have examined the relationship between human rights, population, social development, women and human settlements — and the need for environmentally sustainable development. The World Conference on Human Rights , held in Vienna in 1993, for example, underscored the right of people to a healthy environment and the right to development — controversial demands that had met with resistance from some Member States until Rio.
Critics, however, point out that many of the agreements made in Rio have not been realized regarding such fundamental issues as fighting poverty and cleaning up the environment. Moreover, they say business leaders have used the Rio accords to greenwash their corporate image, giving the impression they have improved their behavior when in many cases this has not been the case.
Other criticisms were that the format of the Summit inhibited the discussion of sustainable development by putting development and environment functions in separate compartments, and uniting trade and development concerns, rather than trade and environment concerns, as would be required if tax, tariff and trade policy were actually to be changed to accommodate environmental concerns.
The preparations for the Earth Summit were marked by unprecedented use of ICT as a key tool for broad-based participation of NGOs in United Nations proceedings, led by the Institute for Global Communications and the International Synergy Institute with the full support of the UNCED Secretariat and set the stage for the subsequent adoption of ICT as the de facto medium for NGO communications.