Large cooperative work systems require work coordination, context awareness and process modelling and enactment mechanisms to be effective. The Serendipity environment provides visual languages for specifying process models and event processing. Enacted models can be modified during or after use and can act as plans of work to be done, describe work in progress, and record work done on a project. Serendipity has been integrated with an Information Systems engineering environment and office automation applications, without modification to these pre-existing tools. Animation of process models allows collaborating users to remain aware of the work contexts of their collaborators. Information about the current enacted process stage is attached to descriptions of changes made to work artefacts, recording the context of work. Such changes are also stored by the process stage, allowing collaborators to review the stage work history. Serendipity's visual event processing language allows users to specify rules and actions triggered by enactment, process or work artefact modification, or tool events. This paper describes Serendipity, our experiences using it, and its architecture and implementation.