Today complex software-based systems often integrate different, previously isolated subsystems where different aspects such as the dynamic behavior or static structure are captured by notations using different paradigms (e.g. statecharts and user interface models, block diagrams for control, …). Therefore, multiple modeling paradigms have to be integrated for their model-driven development. This is especially true when - besides general purpose languages such as UML - domain specific languages are also employed. This first workshop on multi-paradigm modeling addresses this need by providing a forum for researchers and practitioners to discuss the arisen issues. The challenges which result from multi-paradigm modeling in combination with model-driven development can be roughly grouped into language engineering and tool engineering issues. In order to address both of these highly intertwined questions at the workshop, we request to submit papers that address either one or both of them or present an existing tool which supports multi-paradigm modeling: