Disclosed is a method of extracting informative phrases from a full corpus of documents. An index of phrases contained in the full corpus of documents is built. Then, a user specifies a subset of text to analyze. The subset may be defined as: (1) all paragraphs or sentences containing terms selected as defining a subject; (2) all documents in a category; (3) all documents written within a date range; and/or (3) all documents matching a Boolean query of terms. Once the subset is specified, it is analyzed to extract informative phrases. Specifically, the index is queried to retrieve all phrases within the subset. The number of times each of the phases occurs in the subset and in the corpus is counted. Each phrase contained in the subset is scored according to informativeness based on a comparison of a likelihood that the phrase occurs in the subset and a likelihood that the phrase occurs in the corpus as a whole. Only those phrases having an informativeness score above a predetermined value are considered highly informative and extracted.