The Andante and Finale is a composition for piano and orchestra that was reworked by Sergei Taneyev from sketches by Pyotr Ilyich Tchaikovsky for the abandoned latter movements of his single-movement Piano Concerto No. 3 in E-flat, Op. 75.
The core of the music is by Tchaikovsky, but the realisation was by Taneyev, and the decisions on the form, genre and title were jointly made by Taneyev, Tchaikovsky's brother Modest, Alexander Siloti and the publisher Mitrofan Belyayev. It was nevertheless published in 1897 as a work of Tchaikovsky's alone, and even given the posthumous opus number 79 in Tchaikovsky's catalogue.
The Third Piano Concerto and the Andante and Finale are sometimes played together to form a synthetic "complete" concerto.
What we know as the Andante and Finale had its genesis as the slow movement and finale of Tchaikovsky's Symphony in E-flat, a work he started writing in 1892. He abandoned the symphony in December 1892, but after his nephew Bob Davydov chided him, he began reworking it into a piano concerto, his third, which he promised to the French pianist Louis Diémer. The composer finished the outline of the first movement (Allegro brillante) of this concerto in July 1893, then put it aside to continue work on his 6th Symphony (Pathétique). He completed the symphony in August, then returned to the concerto, which he had by this time decided to publish as a single-movement Allegro de concert. The remaining movements were left in sketch form, and there is no evidence that Tchaikovsky had any further use for them. Indeed, there is strong evidence to the contrary. As late as 6 October 1893, a month before his death, he wrote to the Polish pianist and composer Zygmunt Stojowski: "As I wrote to you, my new Symphony is finished. I am now working on the scoring of my new (third) concerto for our dear Diémer. When you see him, please tell him that when I proceeded to work on it, I realized that this concerto is of depressing and threatening length. Consequently I decided to leave only part one which in itself will constitute an entire concerto. The work will only improve the more since the last two parts were not worth very much."