Abstract: [This paper] explores the importance of designing shared browsing user interfaces to support sociability. In particular, several shared browsing interfaces were empirically tested for the extent to which they helped people achieve a sense of shared understanding--or common ground--while surfing the web. We found a) that people generally preferred a shared browser to an unshared browser when shopping online together, and b) that user interface features that enhanced common ground had a greater impact on enjoyment than did features affecting ease of use or functionality. These results suggest that web designers need to take into account supporting sociability when considering the tradeoffs in their user interface designs.