XML permits documents with arbitrary nested context (tag structure). We investigate how this context may be used to aid the task of searching and exploring XML text. We describe the design and implementation of the Cextor system, which includes a context-sensitive text-search engine and a novel technique for organizing and exploring very large search results based on context. A distinguishing feature of this technique is that it does not assume search results are of modest size. Rather, it is designed to cope with search results that are potentially the size of the database. We present the results of an experimental evaluation of Cextor on derived data from the Web. (Cross-referenced as UMIACS-TR-2001-12)