Customization of search results for search queries received from third party sites

A third party website provides a search interface to a general search engine. A site profile of the third party website describes various topics, keywords, or domains that are potentially relevant or of interest to users who access the third party website. The topics are associated with a topical directory, with domains associated with each topic; the domains in a given topic are given various weightings. When a search is submitted to the general search engine from the third party website via the search interface, the general search engine uses the site profile to customize the search results. The search results are customized by weighting the ranking of documents from websites associated with the topics in the site profile. The site profile can be manually or automatically constructed.