Description: This presentation will describe large existing collections of Yizkor Book held at libraries in the U.S. and abroad. The overview will include information on provisions for online searching capability and the availability of books for loan and/or for selected page duplication. An attempt will be made to present an in-depth analysis of over 500 Yizkor Books in terms of the localities (towns and countries), the country and date of publication, the language (primary and secondary), the availability of information on town history, the inclusion of photographs and name lists, and more. _______________________________ At the Libraries of Yad Vashem and the United States Holocaust Memorial Museum, as well as at a number of other institutions around the world, there are collections of books locked in glass-enclosed bookcases. Most often these publications do not circulate. They are treated like rare books only more so because thieves have stolen them. These are the collections of Yizkor Books, memorial books to the victims of the Holocaust. What wealth is stored in these books to make them so valuable that they are worth stealing? The purpose of this paper is to try to find answers to the question posed above by analyzing the contents of a core collection of about 500 Yizkor Books and to study them otherwise in order to establish what information can be gleaned from these material for the study of Jewish history and family genealogy.