This paper studies how to extend the concept of active object 
 into a structure of agent. It first discusses the requirements 
 for autonomous agents that are not covered by simple active objects. 
 We propose then the extension of the single behavior of an active 
 object into a set of behaviors with a meta-behavior 
 scheduling their activities. To make a concrete proposal based on 
 these ideas we describe how we 
 extended a platform of active objects, named {\it Actalk}, into 
 a generic multi-agent platform, named {\it DIMA}. We discuss how this 
 extension has been implemented. 
 We finally report on the application of {\it DIMA} to model 
 economic agent evolution.