While collaboration has become a basic requirement for many development environments, solutions for collaborative modeling are far from being satisfactory. OPCATeam, which relies on Object-Process Methodology (OPM), provides a collaborative modeling environment that can fit generic modeling purposes. OPM, a holistic, bi-modal visual and textual approach to the study and development of systems, integrates the object-oriented and process-oriented paradigms into a single frame of reference. This characteristic, combined with refinement and abstraction mechanisms, makes OPM ideal for business process modeling. OPCATeam features multi-user Client-Server architecture. The server holds a single OPM model for each system in a central repository. OPCATeam has three access permission levels: workgroup, OPM model, and diagram. The diagram permission, which is unique to OPM, aims to reduce the number of conflicts between concurrent updates and preventing modelers from affecting shared elements while allowing them to refine these elements. Users can simultaneously update the model through the clients according to their access permissions. The detailed design implementation is currently being tested.