In the book, Sachs argues that extreme poverty—defined by the World Bank as incomes of less than one dollar per day—can be eliminated globally by the year 2025, through carefully planned development aid. He presents the problem as an inability of very poor countries to reach the "bottom rung" of the ladder of economic development; once the bottom rung is reached, a country can pull itself up into the global market economy, and the need for outside aid will be greatly diminished or eliminated.