This chapter address the question: how do I know, as a professional architect or urban developer, that I do a good job and solve the right problems? The chapter presents a model labelled evidence-based urban development, which departs from an unconventional understanding of the concept of evidence. The model presents four kinds of evidence. The first two, scientific and professional evidence, are closer to the common understanding of evidence-based practice. To this, we add two other forms of evidence: organisational and stakeholder evidence. In the case presented in the chapter, combining information in this way framed the problem to make it possible to act upon. The point of argument in the chapter is that we need all four types of information-that is the definition of the concept of “evidence” here-to be able to make adequate decisions. In this chapter, however, we focus less on organisational and stakeholder knowledge to put light on the dynamic between scientific and professional evidence.