The tighter coupling of enterprises in regard to information system technology has also changed the way business processes are modeled. Modeling interorganizational business processes is necessary in order to gain a profound and unique representation of the processes involved. However this requires a new methodology especially designed for modeling inter-organizational business processes. The United Nation´s Center for Trade Facilitation and Electronic Business (UN/CEFACT) took up the challenge and started to develop such a methodology. The research efforts became known as UN/CEFACT´s modeling methodology (UMM) . UMM enables the business modeler to capture the business knowledge independent of the underlying implementation technology such as ebXML or Web Services. Due to the popularity of the Unified Modeling Language (UML) the UMM is built on top of it. UMM is defined as a UML profile - i.e. a set of stereotypes, tagged values and constraints - in order to customize the UML meta model for the specific purpose of modeling the collaborative space in B2B. Although the standard is well developed and documented, its complexity and mightiness make it difficult for the novice user to perceive from scratch. Therefore a tool, supporting themodeler in creating a validUMMmodel would help those inexperienced with UMM.We have developed such a plug-in for the UML modeling tool Enterprise Architect 1 called UMM Add-In 2.We highlight the main features of the Add-In and show how the tool facilitates the use of the methodology.