In this paper we discuss the management of semi-structured data, i.e., data that has irregular or dynamically changing structure. We describe components of the Stanford Tsimmis Project that help extract semi-structured data from Web pages, that allow the storage and querying of semistructured data, and that allow its browsing through the World Wide Web. A prototype implementation of the Tsimmis system as described here is currently installed and running in the database group testbed.