At the turn of the millennium seven years ago, the international community made a commitment to halve the proportion of people living in extreme poverty and hunger between 1990 and 2015. Now, at the halfway point between the millennium declaration and the deadline, it is clear the world has achieved considerable progress. However, though poverty and malnutrition rates are declining, it is less clear who is actually being helped. Are development programs reaching those most in need, or are they primarily benefiting those who are easier to reach, leaving the very poorest behind? One billion people live on less than $1 a day, the threshold defined by the international community as constituting extreme poverty, below which survival is questionable. That number encompasses a multitude of people living in varying degrees of poverty — all of them poor, but some even more desperately poor than others. To better answer the question of whether the very poorest are being reached, we first divided the population living on less than $1 a day into three categories according to the depth of their poverty: <ul class='square_dot_ul' class="square_dot_ul"> <li>Subjacent poor: those living on between $0.75 and $1 a day</li> <li>Medial poor: those living on between $0.50 and $0.75 a day</li> <li>Ultra poor: those living on less than $0.50 a day1</li> </ul> This allowed us to look below the dollar-a-day poverty line to determine who the poorest people are, where they live, and how each group has fared over time. We found that 162 million people live in ultra poverty on less than 50 cents a day. This is a significant number of people: if all of the ultra poor were concentrated in a single nation, it would be the world's seventh most populous country after China, India, the United States, Indonesia, Brazil, and Pakistan.<br /> <br /> As it is, the ultra poor are overwhelmingly concentrated in one region — Sub-Saharan Africa is home to more than three-quarters of the world's ultra poor. Sub-Saharan Africa is also the only region in the world in which there are more ultra poor than medial or subjacent poor. In contrast, most of Asia's poor live just below the dollar-a-day line; only a small minority of the population is ultra poor.