Why do we need education for sustainability? What is education for sustainability? What are some of the challenges and opportunities a sustainability approach affords? How might a sustainability approach inform science teacher education? This chapter will provide a brief review of the literature on sustainability, environmental education, and education for sustainability, provide a brief history of the concept, and explore how it has been applied in two science teacher education contexts. In addition, by investigating the theoretical and practical challenges of integrating sustainability with the science curriculum in particular, the chapter will provide a basis for understanding the varied approaches taken by other authors in this volume.