Abstract-Modeling is a fundamental concept in software engineering and other system development disciplines. Nowadays the modeling process is supported by powerful modeling tools. Generally speaking, tools which support the definition and usage of self-defined languages are called meta-modeling tools. An important requirement for meta-modeling tools is the interoperability among each other. For instance, interoperability helps to build complex tool chains covering the whole development process. Furthermore, interoperability can also avoid the vendor lock-in effect. Thus, interoperability facilitates the replacement of a tool by a new tool better fitting the customer needs. The objective of this paper is to investigate the current status of interoperability between meta-modeling tools. In more detail, we study the degree of model exchange between meta-modeling tools and look for typical exchange approaches. The study focuses on meta-modeling tools and approaches which are being used in practice or the real world, respectively.