ONE Campaign is an international, non-partisan, non-profit advocacy and campaigning organization that fights extreme poverty and preventable disease, particularly in Africa, by raising public awareness and pressuring political leaders to support policies and programs that save lives and improve futures.

Extreme poverty is the most severe type of poverty, defined by the United Nations (UN) as "a condition characterized by severe deprivation of basic human needs, including food, safe drinking water, sanitation facilities, health, shelter, education and information. It depends not only on income but also on access to services". Historically, other definitions have been proposed within the United Nations.