Ulrich Frank teaches a tutorial on "Simultaneous Development of Languages, Models, and Programs: Boosting the Power of Modeling" at this year's Models Conference in Grand Rapid, MI, USA (MoDELS 25). Usually, the development of DSMLs is separated from the development of corresponding models, resulting in two different representations that are not integrated. Hence, it is not possible to modify a language, while it is being used. The lack of expressivenes of languages used to specify DSMLs is a serious obstacle to representing all relevant knowledge about the targeted domain without redundancy. Also, common approaches to modeldriven development are based on separate representations of models and code, which makes keeping them synchronized extremely challenging. In this tutorial it is demonstrated how these obstacles can be overcome by the use of a multi-level language architecture that allows for a common representation of languages, models and programs.