The United Nations championed the success of the Millennium Development Goals (MDGs) for lifting more than 1 billion people out of extreme poverty, this week. The global improvements led by the goals make it “the most successful anti-poverty movement in history,” said U.N. Secretary-General Ban Ki-moon in the body’s new report.

A caveat that more work is to be done punctuates the U.N.’s self-congratulatory assessment. Some 836 million people live in extreme poverty, defined as an income below $1.25 a day, around the world. It is far fewer than the 1.9 billion people living in extreme poverty in 1990, but still well off from the ambitious goal of eliminating extreme poverty. Ban re-upped his belief that the end of extreme poverty is both possible and can happen soon.

“Following profound and consistent gains, we now know that extreme poverty can be eradicated within one more generation,” he said in a statement accompanying the report. “The MDGs have greatly contributed to this progress, and have taught us how governments, business, and civil society can work together to achieve transformational breakthroughs.”

The MDGs were established in 2000 featuring eight goals all aimed at ending poverty and the conditions that contribute to suffering. Progress was determined based on the state of the world in 1990. The U.N. report shows the major progress made that did not quite reach the targets set by the goals. For example, the number of children dying each year fell from 12.7 million in 1990 to 6 million today, short of the goal to reduce the number by two-thirds. Maternal mortality had the same reduction target and also fell by half – a big reduction in deaths, but short of the goal.

Discussions continue in establishing the next set of goals – called the Sustainable Development Goals (SDGs). The message from the report is that massive global improvements were made in the past decade, but the next 15 years is when the job of ending extreme poverty can be done. The success is attributed to the MDGs, making the SDGs all the more important when thinking about what can be accomplished by 2030.

“The MDGs worked at all levels – global, national and local, rallying not just diplomats and technocrats in conference buildings but communities gathering in village squares,” said Ban.

That all assumes that the MDGs caused change. There is reason to believe the conclusion is wrong. U.N. Population Fund statistician Howard Freidman analyzed the impact of the MDGs a few years ago. Looking at progress on the MDG indicators since 1992, Friedman found that significant accelerations towards the targets started before the MDGs were established. The MDGs did not necessarily cause countries to reduce hunger, child mortality, and poverty, they reflected the changes that were already taking place.

The findings are similar to that of Center for Global Development researchers Charles Kenny and Andy Sumner’s 2011 working paper on the MDGs. They found the MDGs did galvanize public support, changes in policies, and more aid spending. But the goals leading to improvements is a harder thing to prove.

“The causal chain from international agreement to policy change to development outcomes is a long one with many confounding influences,” concluded Kenny and Summer. “Given that, it is impossible to say with any certainty what was the impact of the MDGs.”

The U.N. sees it differently.

“The MDG report confirms that goal setting can lift millions of people out of poverty, empower women and girls, improve health and well-being, and provide vast new opportunities for better lives,” according to the press release accompanying the report, from the U.N. Development Programme.

The SDGs as they stand include 17 goals and 169 targets. World leaders meet in Ethiopia this month to figure out how to fund achieving the goals and targets. In September, meetings at the United Nations in New York City will finalize the draft targets and the global development agenda for the next 15 years will be set.

Whether or not the MDGs led to progress over the past 15 years, the U.N. is already thinking about the next 15 years.

“As we look ahead, we must do more to reach those who are most vulnerable, are not counted and have not shared the improvements of the past 15 years,” said Ban, in remarks delivered at the launch of the report. “We cannot allow hard-won and fragile gains to be diminished or reversed.”