Much recent writing concerning the early eighteenth-century sonata has focused on a subgenre that appropriates stylistic elements from more fully scored works. Thus several of J. S. Bach’s solo and trio sonatas signify the concerto in certain movements by adopting ritornello form and establishing instrumental roles of ‘soloist’ and ‘orchestra’, only to undermine the integrity of these roles during the course of a movement. These Sonaten auf Concertenart, and a number of similar examples by Bach’s German contemporaries, have been viewed as responses to Vivaldi’s solo concertos and especially his so-called ‘chamber concertos’, which feature similar kinds of role playing. This study, by re-examining the phenomenon of the sonata in concerto style from a number of perspectives, shows that the genre was more widespread and its origins and meanings more complex than previously recognized. Evidence for this revised view takes the form of generic titles on manuscripts and prints; music by German, Italian and French composers spanning much of the eighteenth century, from Molter to Mondonville to Mozart; some three dozen sonatas by Telemann, who exhaustively explored the genre over several decades and was perhaps its originator in Germany; and literary amalgamations of genre indicative of a broader eighteenth-century fascination with mixed types.