Sustainability is internationally often emphasized as an essential aim of higher education, but more as a principle than on the practical level. This is also obvious in the academic education of primary teachers in Finland. Therefore, it is a great challenge for Finnish teachers to include sustainability in their teaching and everyday life in schools. The aim of this article is to critically analyze why the implementation of sustainability in teacher education is so intricate and to discuss possible solutions with Finland--a country highly valued for its education--as an example. The article reports outcomes from educational policy documents and research on educational, philosophical, scientific and social aspects of sustainability, including evaluation of how sustainability has been implemented in schools and at universities, especially among teacher educators. In addition, the article builds on analyses of comprehensive university strategies and primary school teacher education programs. We found these reasons for the ignoring of sustainability in the Finnish teacher education: sustainability is in conflict with overall trends in society and politics, teacher education takes place at universities and is based on separate academic disciplines. Sustainability is also intricate because it is strongly connected to ecological literacy and it is value dependent. Universities need to overcome these obstacles and become forerunners in the sustainability process.