For a long time, the symphony was believed to be a work of Schubert’s last year, 1828. It was true that, in the last months of his life, he did start drafting a symphony – but this was the work in D major now accepted as Symphony No. 10, which has been realized for performance by Brian Newbould. In fact, we now know that the 'Great' was largely composed in sketch in the summer of 1825: that, indeed it was the work to which Schubert was referring in a letter of March 1824 when he said he was preparing himself to write 'a grand symphony'. By the spring or summer of 1826 it was completely scored, and in October, Schubert, who was quite unable to pay for a performance, sent it to the Gesellschaft der Musikfreunde with a dedication. In response they made him a small payment, arranged for the copying of the orchestral parts, and at some point in the latter half of 1827 gave the work an unofficial play-through (the exact date and the conductor are unknown) – though it was considered too long and difficult for the amateur orchestra of the conservatory.
A recent hypothesis suggests that the symphony may have received its first performance on 12 March 1829 in a Concert spirituel at the Landständischer Saal in Vienna. The evidence for this hypothesis is slender, however, and it contradicts contemporary sources which prove that Schubert's Symphony No. 6 (also in C major) was performed at this instance. In 1836 Schubert's brother Ferdinand attempted to perform the final movement alone, yet there is no proof that it was actually played in public.
In 1838, ten years after Schubert's death, Robert Schumann visited Vienna and was shown the manuscript of the symphony at the Gesellschaft der Musikfreunde by Ferdinand Schubert. He took a copy that Ferdinand had given him back to Leipzig, where the entire work was performed publicly for the first time by Felix Mendelssohn at the Leipzig Gewandhaus on 21 March 1839. Schumann celebrated the event in the Neue Zeitschrift für Musik with an ecstatic article in which, in a phrase destined to become famous, he hailed the symphony for its 'heavenly length'. Legend claims that, during a rehearsal of the first movement, one musician was reported as asking another if he had managed to hear a tune yet. On the other hand, having heard its first performance, Schumann is reported to have said he thought it the greatest instrumental work since the death of Beethoven.