Business process modelling is an integral component of Business Process Management and is, by na-ture, a collaborative act that involves many stakeholders. Process modelling initiatives, while not able dependent on technology, are often supported by one or more dedicated commercial software tools. However, while a broad range of process modelling aspects have been researched, little is known about how to support modelling with collaborative tools. Accordingly, we aim to elicit a better under-standing of the nature of collaborative process modelling and its support in modelling tools. Our study is based on the assumption that tool designers hold certain conceptions about how people use model-ling tools and that such conceptions become inscribed in the tools. By analysing and classifying a sample of modelling tools, with regards to their collaborative features for supporting the modelling task, we aim to elicit an understanding of the collaborative aspects of process modelling. Our study finds only very fragmented collaborative functionality across our tool selection and builds on these findings to suggest a high-level architecture for collaborative support in process modelling tools.