The motivation of semantic wikis is to make acquisition, maintenance, and
mining of formal knowledge simpler, faster, and more flexible. However, most
existing semantic wikis have a very technical interface and are restricted to a
relatively low level of expressivity. In this paper, we explain how AceWiki
uses controlled English - concretely Attempto Controlled English (ACE) - to
provide a natural and intuitive interface while supporting a high degree of
expressivity. We introduce recent improvements of the AceWiki system and user
studies that indicate that AceWiki is usable and useful