Many software acquisition projects fail. The reason is often the underestimation of their complexity: not only the work of the project's staff has to be coordinated but also the more sumptuous inter-project coordination has to be performed. Goal of this work is to develop a better understanding of software acquisition processes. Appropriate process modeling and simulation techniques are investigated which support this understanding. We use both established techniques like modeling and simulation with System Dynamics and techniques which are newly developed within the framework of this dissertation like the process modeling architecture GARP and process-oriented interactive simulation.