Harmony was one of the areas in which Romantic music made the greatest technical advances. On the one hand, composers learned to use harmony to underpin melody in such a way as to bring out its emotionality. Romantic melody is, in fact, inseparable from harmony. In the Romeo and Juliet Love theme, for example, a rich new chord goes hand in hand with the warm upward scoop of the melodic line in measure 5.

On the other hand, harmony was savored for its own sake, and composers experimented freely with new chord forms and new juxtapositions of chords. These, it was found, could contribute potently to those mysterious, sinister, rapturous, ethereal, or sultry moods that Romantic composers sought to evoke.

Chromaticism is a term for a style that liberally employs all twelve notes of the chromatic scale (see page 23). Romantic composers pursued chromaticism to a greater extent than Baroque and Classical ones, in order to expand the expressive range of both their melodies and their harmony. If you look closely at the Romeo and Juliet theme, you will find nearly all twelve notes of the chromatic scale included — something that seldom happens in earlier music. Chromaticism was carried furthest in the nineteenth century by Richard Wagner, and further yet by the early twentieth-century modernists.