: One of the keys to success for applications of mobile and/or intelligent agents in large-scale open systems such as Internet is the ability of heterogeneous agents to cooperate and negotiate, and meet if they are mobile. This heterogeneity support requires the adoption of standards at the underlying distributed system level to support interoperability in agent management, mobile agent transport, and agent communication transport. This paper shows how both OMG standards and a modular architecture based on three kinds of component -- agent mobility kernel, agent communication tools, and agent activity kernel -- makes it possible to build a variety of heterogeneous mobile agent platforms with ad hoc features while preserving interoperability. 1 YET ANOTHER JAVA MOBILE AGENT PLATFORM?