The Hammered Dulcimer played an important role in Anglo- American folk and popular music during the 18th, 19th, and early 20th centuries. This booklet gives a brief history of its development in the Middle East and Europe, its musical use and social function in America, and how it was manufactured and marketed in 19th century America. In the appendices are given a list of United States patents granted for improvements in dulcimer design, a list of known makers, biographical information on the musicians interviewed in the course of this research, a checklist of dulcimers in the Smithsonian Institution, and a selected discography.