In the process of developing P2P systems simulation has proved to be an essential tool for the evaluation of existing and conceived P2P systems. So far, in practice there has been a clear separation between a simulation model of a P2P system and a real P2P system that operates on a real physical network. This separation hinders the transition of models to real systems and the evaluation of already deployed systems by means of simulation. This work tries to bridge this gap by proposing a methodology and a framework for the simulation-based development of P2P systems. In our approach, an initial model of a P2P system is iteratively transformed into the intended real P2P system. The presented framework effectively supports a developer in modelling, simulating and ultimately developing P2P systems. We demonstrate the validity of our approach and the framework by constructing an example P2P application. This application is simulated in a series of experiments as well as deployed in a large...