A string stretcher has a body with a stretcher axis of rotation about which to rotate the string stretcher when positioned transverse to the fingerboard. At least one support member has an upwardly facing support surface for selectively urging and holding the selected string above the fingerboard. A first stretching member has a first stretching surface spaced from the stretcher axis of rotation for contacting the selected string at a first string location to urge the selected string across the fingerboard in a first direction during rotation. A second stretching member has a second stretching surface oppositely facing with respect to the first stretching surface, for contacting the selected string at a second string location opposite the stretcher axis of rotation from the first stretching surface to urge the selected string across the fingerboard in a second direction substantially opposite the first direction.