The work has its origins, like the composer's Scottish Symphony and the orchestral overture The Hebrides (Fingal's Cave), in the tour of Europe which occupied Mendelssohn from 1829 to 1831. Its inspiration is the colour and atmosphere of Italy, where Mendelssohn made sketches but left the work incomplete:
"This is Italy! And now has begun what I have always thought... to be the supreme joy in life. And I am loving it. Today was so rich that now, in the evening, I must collect myself a little, and so I am writing to you to thank you, dear parents, for having given me all this happiness."
In February he wrote from Rome to his sister Fanny,
The Italian symphony is making great progress. It will be the jolliest piece I have ever done, especially the last movement. I have not found anything for the slow movement yet, and I think that I will save that for Naples.
The Italian Symphony was finished in Berlin, 13 March 1833, in response to an invitation for a symphony from the London (now Royal) Philharmonic Society; he conducted the first performance himself in London on 13 May 1833, at a London Philharmonic Society concert. The symphony's success, and Mendelssohn's popularity, influenced the course of British music for the rest of the century. However, Mendelssohn remained unsatisfied with the composition, which cost him, he said, some of the bitterest moments of his career; he revised it in 1834 and even planned to write alternate versions of the second, third, and fourth movements. He never published the symphony, and it appeared in print only in 1851; thus it is numbered as his 'Symphony No. 4', although it was in fact the third in order of composition.
The joyful first movement, in sonata form, is followed by an impression in the sub-dominant key D minor of a religious procession the composer witnessed in Naples. The third movement is a minuet in which French Horns are introduced in the trio, while the final movement (which is in the minor key throughout) incorporates dance figurations from the Roman saltarello and the Neapolitan tarantella. It is among the first large multi-movement works to begin in a major key and end in the tonic minor, another example being Brahms's first piano trio.
A typical performance lasts about half an hour.