Abstract Discussion and annotations are two important activities in collaborative work with documents. HERD (Hypertext Environment for Reasoned Discourse) is an issue-based information system which effectively supports informal discussions about requirements documents. In one case study, HERD was used to support a discussion; while in another case study, HERD was used during annotation of an online textbook. The hypothesis was that the processes of annotation and discussion are sufficiently similar that a discussion system could support annotation. Although HERD provided a useful environment for discussion, it was not especially suitable for annotation, because it did not allow users to directly point to the document which was being annotated. Furthermore, HERD enforced a fixed set of node and link types which both for discussion and, particularly, for annotation were not always suitable for the users. Further evidence for the difference between discussion and annotation was established via an automatic analysis of word patterns. A system called MUCH (Multiple Users Creating Hypertext) was developed to support collaborative authoring. The MUCH system supports document creation and includes features for “discussing”, “authoring”, “annotating”, and “document reuse”. The annotation subsystem was tested by performing an experiment on a few sections of the same online hypertext used in the HERD experiments. The users of HERD and MUCH found the MUCH system to be significantly better than the HERD system in supporting annotation. The two systems were compared and the data of discussion and annotation case studies was analyzed. Another set of experiments was performed and a considerable number of similarities between discussion and annotation were found. Design issues relevant to discussion and annotation are reviewed.