The viola d'amore is a stringed musical instrument sharing some characteristics with the viol family. Like viols, it has a flat back and intricately carved head at the top of the peg box, but it is unfretted, and played much like a violin, being held horizontally under the chin. It is about the same size as the modern viola.

The viola d'amore usually has fourteen strings. Seven of them are playing strings, which are sounded by drawing a bow across them, just as with a violin. The other seven are sympathetic strings which are not played directly but vibrate in sympathy with the notes played. A common variation is six playing strings, and instruments exist with as many as fourteen sympathetic strings alone. Despite the fact that the sympathetic strings are now thought of as the most characteristic element of the instrument, it is thought that some early examples may have lacked them.

There is no standard tuning scheme for the strings as there are with modern string instruments. Players will frequently need to change the tuning from one piece to another. However, the range of the instrument is usually from the D below middle C to the D two octaves above it.

Largely thanks to the sympathetic strings, the viola d'amore has a particularly sweet and warm sound. Leopold Mozart, writing in his Versuch einer gründlichen Violinschule, said that the instrument sounded "especially charming in the stillness of the evening."