UN/CEFACT´s Modeling Methodology (UMM) is a well accepted approach to define inter-organizational business processes. UMM models should be managed in a registry for two reasons: Firstly, business partners supporting the process can find it and bind to it. Secondly, a model - or more important parts thereof - may be reused in another model of an inter-organizational process. Accordingly, registering one model as one object in a registry is not appropriate. Those parts of a model that may be reused must become registry objects themselves. Extracting parts of a model results in objects that are logically inter-related. Thus, a registry model taking care of these inter-relationships is needed. In this paper we present a so-called business collaboration registry model that sits on top of the ebRIM (ebXML registry information model) in order to manage UMM business collaboration models in an ebXML registry. Furthermore, we outline the registry management functions for maintaining models in the registry.