- A concerto (/kənˈtʃɛərtoʊ/; plural concertos, or concerti from the Italian plural) is, from the late Baroque era, mostly understood as an instrumental composition, written for one or more soloists accompanied by an orchestra or other ensemble. The typical three-movement structure, a slow movement (e.g., lento or adagio) preceded and followed by fast movements (e.g. presto or allegro), became a standard from the early 18th century.