There is a growing interest of flexibility in urban plans, both within the planning profession but also by private investors. The collective idea, both among planners and literature, is that the urban is under a constant transformation. Further, flexibility in planning could be found as key of keeping updated to this constant development. Through the theories of temporary and tactical urbanism the positive and negative aspects of flexibility will be discussed and explored. The combination of literature analysis and interviews has formed the basis for creating an understanding how the practical field and literature interprets flexibility in a transforming era in Sweden. According to literature and interviews, this study has shown that flexibility within the regulations of the detailed development plan is key for cities to adapt to new circumstances.