Low carbon development is crucial for mitigating emissions that lead to climate change and for enabling development in a carbon constrained world. Low carbon development is being pursued by high income countries and emerging emitters to reduce emissions, increase economic growth and firm competitiveness. At the same time, low carbon development is an option for lower income countries to access modern energy, low carbon technology and to reduce poverty. This chapter elaborates what low carbon development is, why it is needed, how it is defined, how it differs from other key concepts in the field of environment and development and how to achieve low carbon development in practice.