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.

Sachs explains that countries, like patients, are complex systems, requiring differential diagnosis, an understanding of context, monitoring and evaluation, and professional standards of ethics.

Many factors can affect a country's ability to enter the world market, including government corruption; legal and social disparities based on gender, ethnicity, or caste; diseases such as AIDS and malaria; lack of infrastructure (including transportation, communications, health, and trade); unstable political landscapes; protectionism; and geographic barriers.

Sachs places a great deal of emphasis on the United Nations' Millennium Development Goals (MDGs) as a first step towards eliminating extreme poverty, which affected approximately 1.1 billion people worldwide at the time of publication.

He also offers some specific, immediate solutions, such as increasing the availability of anti-malarial bed nets in sub-Saharan Africa, and encourages debt cancellation for the world's poorest countries.