This chapter provides an introduction to the research by recalling how sustainability emerged, particularly in the so-called media development sector. It is mainly defined by an indicator provided by the OECD that is tacitly recognised by all stakeholders. Instead of looking at the concept itself, this book focuses on the discourse assessing sustainability and what it says about the values and unspoken assumptions it conveys. The objective is to see how the evaluation practice itself is re-interrogated by this sustainability criterion. This evidence-based study starts with a view from above (how evaluators assess sustainability). It is then confronted with the bottom view of the actors in the field before returning to the evaluators to discuss the conditions of production of these discourses.