Roméo et Juliette is a symphonie dramatique, a large-scale choral symphony by French composer Hector Berlioz, which was first performed on 24 November 1839. The libretto was written by Émile Deschamps, and the completed work was assigned the catalogue numbers Op. 17 and H.79. It is based on Shakespeare's play Romeo and Juliet; it is regarded as one of Berlioz's finest works, and it is among the most original in form. The score is Berlioz's most comprehensive and detailed programmatic piece.
Initial inspiration came from a performance he witnessed in 1827 of Romeo and Juliet (in David Garrick's edited version) at the Odéon Theatre in Paris. The cast included Harriet Smithson, who also inspired Berlioz's Symphonie fantastique. In his Memoirs, Berlioz describes the electrifying effect of the drama:
... to steep myself in the fiery sun and balmy nights of Italy, to witness the drama of that passion swift as thought, burning as lava, radiantly pure as an angel's glance, imperious, irresistible, the raging vendettas, the desperate kisses, the frantic strife of love and death, was more than I could bear. By the third act, scarcely able to breathe—it was as though an iron hand had gripped me by the heart—I knew that I was lost. I may add that at the time I did not know a word of English; I could only glimpse Shakespeare darkly through the mists of Letourneur's translation; the splendour of the poetry which gives a whole new glowing dimension to his glorious works was lost on me. ... But the power of the acting, especially that of Juliet herself, the rapid flow of the scenes, the play of expression and voice and gesture, told me more and gave me a far richer awareness of the ideas and passions of the original than the words of my pale and garbled translation could do.
The range of feeling and mood as well as poetic and formal invention which Berlioz found in Shakespeare had a strong influence on his music, making a direct musical setting of Shakespeare's work only natural. In fact, he had been planning a musical realisation of Romeo and Juliet for a long time before 1838, but other projects intervened. Emile Deschamps (the librettist of the work) says that he and Berlioz worked out a plan for the symphony shortly after the Odéon's 1827-28 season. Indeed, it may be the case that Roméo et Juliette's genesis is intertwined with other works composed before the composer left for his Prix de Rome sojourn of 1830-32. Sardanapale, the cantata with which Berlioz finally won the Prix de Rome in 1830, includes the melodic material of both the Roméo seul ("Romeo alone") portion of the second movement and the Grande fête chez Capulet ("Great banquet at the Capulets").