Education for Sustainable Development (ESD) is a contested concept and this chapter will introduce the reader to the range of definitions and important debates and the particular challenges and opportunities of introducing ESD within the constraints of the further education and skills sector. It will encourage readers to question themselves regarding their current understanding of ESD policy and theory and how this is influencing them in their professional practice and in their personal lives. This will be returned to in the concluding chapter so that the reader may evaluate the impact the text has had on their professional and/or personal lives. It will encourage the reader to review and question some of the potential barriers (both institutional and personal) that may exist in their attempts to embed ESD in their practice.