When rich country leaders talk of fighting poverty, the emphasis is often on improving economic growth in their poorer neighbours.
Brazil's favelas are proof that inequality is a key problem, the UNDP says
But according to a new report from the United Nations, that alone will fail to produce meaningful poverty reduction.
Instead, it says, countries need to focus on reducing inequality - between rich and poor, between men and women and between regions.
Rich states also need to give more aid and improve its quality, the UN says.
Each year, the United Nations Development Fund (UNDP) releases its huge Human Development Report, designed around a list which rates countries not by economic power but by a series of indicators reflecting quality of life.
Since 2000, it has also covered progress towards the UN's Millennium Development Goals (MDGs), which include halving poverty, cutting child mortality and providing clean water and sanitation.
This year's report shows that for 450m people, conditions have deteriorated over the past fifteen years.
Of the 18 countries in that category, 12 are in sub-Saharan Africa, their plight the result partly of the HIV/Aids pandemic.
Inequality is a key factor in whether the MDGs are being achieved, the report says.
On one level, international inequalities play a part, with the poorest 40% of the world's population sharing only 5% of global income.
But the report's author, Kevin Watkins, says that inequalities within countries are just as big a problem.
"Anybody questioning whether income distribution matters might reflect on the fact that the poorest 10% of Brazilians are poorer than their counterparts in Vietnam, a country with a far lower average income," he says.
Brazil is ranked 63 on the Human Development Index, while Vietnam is number 103.
The report also points to success in Bangladesh at reducing infant mortality - well ahead of similar efforts in high-growth countries such as China and India.
And females are often getting a worse deal than males, it says, limiting the positive effects of economic development.
In India, for example, half again as many girls die between the ages of one and five as do boys.
Responsiblities for the rich
Elsewhere, the report says that poorer countries need to work harder on issues such as corruption - and richer countries have to strengthen their commitment to keep their end of the development bargain.
DR Congo's natural resources helped feed its civil war
Aid needs to be better targeted, more predictable, with fewer strings and better co-ordination between donors.
And trade and security are also key issues, with the current trade round needing to live up to its development rhetoric - instead of, as at present, seeing agricultural subsidies actually increase.
Peace-making and peace-building efforts also need to be a higher priority, the UNDP says, noting that poorer countries are much more likely to descend into civil war than richer ones.
"What is clear is that poverty is part of the cycle that creates and perpetuates violent conflict - and that violent conflict feeds back to reinforce poverty," the report says.
There is a direct incentive for rich countries to help break the cycle: the risk of creating safe havens for terrorist and criminal groups.
To do so, the UNDP argues, rich countries need to cut back on flows of small arms and give more aid to conflict-prone countries - countering a tendency to concentrate aid on "success stories".
But they also need to get tough on natural resource mismanagement, the UNDP argues.
The call follows a string of UN reports into the Democratic Republic of Congo, where a desire to capture mineral and other resources among neighbouring countries and their client militias has perpetuated civil strife which has killed more than 3 million people.
Transnational companies based in rich countries need to be more transparent in their dealings, the UNDP says.
"The international legal framework proposed by the British government-sponsored Commission on Africa to ensure that corrupt pracitices by transnational companies overseas are prosecuted at home - as already practised under US law - should be developed as a priority," it says.