This paper presents a new model for supporting collaborative, integrated software development utilising multiple textual and graphical views. Views can be asynchronously edited by different developers using separate versions. Versions can be incrementally merged, with merge conflicts detected and presented. Synchronous editing of views by different developers is also supported. View updates are broadcast to other users and are incrementally incorporated as required in their alternative versions. The new model is illustrated by its use in a software development environment for an object-oriented language.