In this paper we propose a new wiki concept — light constraints — designed to encode community best practices and domain-specific requirements, and to assist in their application. While the idea of constraining user editing of wiki content seems to inherently contradict “The Wiki Way”, it is well-known that communities of users involved in wiki sites have the habit of establishing best authoring practices. For domain-specific wiki systems which process wiki content, it is often useful to enforce some well-formedness conditions on specific page contents. This paper describes a general framework to think about the interaction of wiki system with constraints, and presents a generic architecture which can be easily incorporated into existing wiki systems to exploit the capabilities enabled by light constraints. Categories and Subject Descriptors I.7.2 [Document Preparation]: Hypertext/hypermedia; H.3.5 [Online Information Services]: Web-based Services General Terms Design Keywo...