We describe a platform for the portable and secure execution of mobile agents written in various interpreted languages on top of a common run-time core. Agents may migrate at any point in their execution, fully preserving their state, and may exchange messages with other agents. One system may contain many virtual places, each establishing a domain of logically related services under a common security policy governing all agents at this place. Agents are equipped with allowances limiting their resource accesses, both globally per agent lifetime and locally per place. We discuss aspects of this architecture and report about ongoing work. Keywords: migration, multi-language, interpreter, Tcl, C, byte code, Java, persistence, authentication, security domain. 1. Introduction Mobile agents have raised considerable interest as a new concept for networked computing, and numerous software platforms for various forms of mobile code have recently appeared and are still appearing [CGH95, CMR+...