In 1977, Maathai founded the Green Belt Movement, a grassroots environmental non-governmental organization, which has now planted over 30 million trees across Kenya to prevent soil erosion. She has come to be affectionately called "Tree Woman." Since then, she has been increasingly active on both environmental and women's issues.
Maathai was also the former chairperson of Maendeleo Ya Wanawake (the National Council of Women of Kenya). In the 1980s her husband Mwangi Mathai, a politician whom she had married in 1969, divorced her, saying she was too strong-minded for a woman, and that he was unable to control her. The judge in the divorce case agreed with the husband, and Wangari was put in jail for speaking out against the judge, who then decreed that she must drop her husband's surname. In defiance, Wangari chose to add an extra "a" instead.[1]
During the regime of President Daniel Arap Moi, she was imprisoned several times and violently attacked for demanding multi-party elections and an end to political corruption and tribal politics. In 1989 Maathai almost single-handedly saved Nairobi's Uhuru Park by stopping the construction by Moi's business associates of the 60-story Kenya Times Media Trust business complex.
In 1997, in Kenya's second multi-party elections marred by ethnic violence, she ran for the country's presidency, but her party withdrew her candidacy. Nevertheless, she was a minor candidate among several contenders.
In 2002 Maathai was elected to parliament when the National Rainbow Coalition, which she represented, defeated the ruling party Kenya African National Union. She has been Assistant Minister in the Ministry of Environment, Natural Resources and Wildlife since 2003. She founded the Mazingira Green Party of Kenya in 2003.
On 28 March 2005, she was elected as the first president of the African Union's Economic, Social and Cultural Council.
In 2006 she was one of the eight flag bearers at the 2006 Winter Olympics Opening Ceremony. Also on May 21, 2006 she was awarded an honorary doctorate by and gave the commencement address at Connecticut College.
In January of 2007 Maathai will host the Global Young Greens conference in Nairobi, where more than 120 young delegates of environmental, civil rights, peace, and social justice youth movements as well as youth organisations of green parties from all over the world are expected to come.
On January 28, 2007, Maathai returned to Benedictine College for the first time in over 15 years and spoke to the students at her alma mater.
In 2008, she will co-host the Global Greens Nairobi conference, which is expected to draw over 1,000 Greens from dozens of Green Parties around the planet.
Her autobiography, Unbowed: One Woman’s Story, was released in September 30, 2006.