Model integration is inescapable: any non-trivial system will be too large to fit sensibly in a single model. The model will have to be split, maybe into different aspects or languages, different modeler roles and tasks, different phases of the software development life cycle, etc. In Domain-Specific Modeling, the possibilities to integrate models are fundamentally better than with general-purpose languages as the company has full access to the language definitions. We describe and compare different ways to integrate DSM models, based on real world experience of what has been shown to work in practice on industrial scales.