Maathai was educated in the United States at Mount St. Scholastica College (now Benedictine College; B.S. in biology, 1964) and at the University of Pittsburgh (M.S., 1966). In 1971 she received a Ph.D. at the University of Nairobi, effectively becoming the first woman in either East or Central Africa to earn a doctorate. She began teaching in the Department of Veterinary Anatomy at the University of Nairobi after graduation, and in 1977 she became chair of the department.

While working with the National Council of Women of Kenya, Maathai developed the idea that village women could improve the environment by planting trees to provide a fuel source and to slow the processes of deforestation and desertification. The Green Belt Movement, an organization she founded in 1977, had by the early 21st century planted some 30 million trees. Leaders of the Green Belt Movement established the Pan African Green Belt Network in 1986 in order to educate world leaders about conservation and environmental improvement. As a result of the movement’s activism, similar initiatives were begun in other African countries, including Tanzania, Ethiopia, and Zimbabwe.

In addition to her conservation work, Maathai was also an advocate for human rights, AIDSprevention, and women’s issues, and she frequently represented these concerns at meetings of the United Nations General Assembly. She was elected to Kenya’s National Assembly in 2002 with 98 percent of the vote, and in 2003 she was appointed assistant minister of environment, natural resources, and wildlife. When she won the Nobel Prize in 2004, the committee commended her “holistic approach to sustainable development that embraces democracy, human rights, and women’s rights in particular.” Her first book, The Green Belt Movement: Sharing the Approach and the Experience (1988; rev. ed. 2003), detailed the history of the organization. She published an autobiography, Unbowed, in 2007. Another volume, The Challenge for Africa (2009), criticized Africa’s leadership as ineffectual and urged Africans to try to solve their problems without Western assistance. Maathai was a frequent contributor to international publications such as the Los Angeles Times and the Guardian.