Although most symphonies have four movements, this symphony has only three, which was still common in the early classical period:
The symphony features the fanfares and flourishes typical of the "festive symphony" or "trumpet symphony", which is characteristic of Austrian symphonic writing in C major. This is the first of Mozart's C-major symphonies to exhibit this character, but the style would be revisited in his subsequent two works in this key, the 36th and 41st symphonies.
The first movement is written in sonata form but also contains many styles and formal aspects of an Italian overture. There is no expositional repeat. The expositional coda contains an overture-like crescendo which is not included in the recapitulation. The development is based entirely on new material. The recapitulation on the exposition's first theme is abbreviated and interrupted by a brief development of that theme. Finally, the movement's coda contains nearly all of this first theme creating the appearance of a reverse-recapitulation common in Italian overtures.
Alfred Einstein advanced a theory in the third edition of the Köchel catalogue that the Minuet K. 409 was written at a later date by the composer for this work. However, there is no proof in the sources to support his thesis. Also, K. 409 calls for two flutes in its orchestration which does not match the rest of the symphony.