The Appalachian dulcimer (or mountain dulcimer) is a fretted string instrument of the zither family, typically with three or four strings. It is native to the Appalachian region of the United States. The body extends the length of the fingerboard, and its fretting is generally diatonic.

Although the Appalachian dulcimer first appeared in the early 19th century among Scots-Irish immigrant communities in the southern Appalachian Mountains, the instrument has no known precedent in Ireland or Scotland.^{[citation needed]} However, several diatonic fretted zithers exist in Continental Europe that have a strong similarity to the dulcimer. Jean Ritchie and others^{[citation needed]} have speculated the Appalachian dulcimer is related to similar European instruments like the langeleik, scheitholt and épinette des Vosges.

Charles Maxson, an Appalachian luthier from Volga, WV, speculated that early settlers were unable to make the more complex violin in the early days due to lack of tools and time. This was one of the factors which led to the building of the dulcimer, which has less dramatic curves. He too cited the langeleik, scheitholt and épinette des Vosges as ancestor instruments.^{[citation needed]}