Like sonata form, rondo forms have a long history. Where sonata emanates from Baroque dance movements (coming mostly from Italy), rondo has a longer history whose origins are in a French instrumental genre—the rondeaux—that was characterized by an alternation of refrains and contrasting couplets. Within an instrumental sonata or symphonic work, rondos are generally found in fast finales or in slow second movements. Probably because rondos are lighter in character, they are almost never found as a first movement.
Conceptually, rondo is quite simple. The form consists of refrains that alternate with episodes. The refrain material is the same throughout the course of a movement—sometimes slightly embellished or abbreviated—and is always heard in the tonic key. Episodes contrast with refrains tonally, and usually thematically as well. Unlike refrains, a rondo’s episodes do not have to be the same in the course of a movement. So on a large scale, a typical rondo will articulate an ABAC … A form; A stands for refrain, B and C indicate episodes containing unique thematic material. The ellipsis mark (…) indicates that the precise number of refrains and episodes is variable, though the 5-part (ABACA) rondo is certainly the most common.
Though conceptually simple, in practice, rondo may be the most difficult form to describe theoretically and engage with analytically. This is primarily because different composers used the simple rondo schematic above in different ways. To help you manage these deviations, we will classify rondos into two types: (1) five-part rondo (ABACA), and (2) sonata rondo (ABACABA). The primary difference between the types, which we will discuss in more detail in the other rondo resources,is that in a sonata rondo, the first refrain and first episode constitute a complete sonata exposition that is recapitulated (with the episode transposed to the tonic key) in the third refrain and episode. Learning to recognize the types of thematic function most common in rondo forms is an important first step.