The importance of search facilities on a website grows with the size of the content being served. User expectations for internal site search are greatly influenced by global web search engines, requiring developers of web applications to go beyond basic search functionality. In this thesis, a domain-specific language (DSL) for internal site search is designed and integrated as a sublanguage of WebDSL (the base language). WebDSL is an existing DSL for web development. Through an exploration of the problem and solution space, the facets related to internal site search are explained. Furthermore, an iterative approach applied at the development of the DSL is presented. This approach is based on the use of existing base language constructs as core language. The core languages provide access to implemented search features. Linguistic abstractions are added on top of the core languages, constituting the eventual interface of the language. Evaluation by means of enriching two web applications with search features show that the DSL has substantial coverage of the internal site search domain.