The paper discusses several aspects of Wikipedia as an online community. It analyses the role of public opinion in discussions, disputes, and the solution of conflictsamong the users of the online encyclopaedia. Noelle-Neumann’s (1974, 1984) Theory of public opinion as social control is used as a theoretical background to analysethree levels of public opinion in Wikipedia: The meta-level, the discussion-level, and the article-level. The use of the Mediawiki-software for content-analyses is discussed and illustrated by a qualitative analysis of a case study. Subject of the casestudy is a fierce dispute about design and content of user pages in the German language version of Wikipedia.