Holocaust survivors took their role as witnesses extremely seriously. This phenomenon becomes evident when we take into account that the large Holocaust collections of the world in archives and libraries have accumulated nearly 1,000 Yizkor books (memorial books) and more than 100,000 survivor testimonies. These collections continue to increase to this day, despite the dwindling numbers of survivors. This essay addresses the personal and communal role of the survivors in shaping the memory not only of the Holocaust, but also of the Jewish world that went before it.