This article is designed for law librarians based outside the United States. The paper, written by Marcia Zubrow, provides basic information about the United States legal system and its sources. This background foundation to the article is important in understanding how to effectively use the two major U.S. databases, Lexis and Westlaw. The author describes the contents of the two databases within the context of the background information. Search techniques, including advance searching strategies, are described.