The solo concerto, a vast and important repertory of the early to mid eighteenth century, is known generally only through a dozen concertos by Vivaldi and a handful of works by Albinoni and Marcello. The authors aim to bring this repertory to greater prominence and have, since 1995, been involved in a research programme of scoring and analysing over nine hundred concertos, representing nearly the entire repertory available in early prints and manuscripts. Drawing on this research, they present a detailed study and analysis of the first-movement ritornello form, the central concept that enabled composers to develop musical thinking on a large scale. Their approach is firstly to present the ritornello form as a rhetorical argument, a musical process that dynamically unfolds in time; and secondly to challenge notions of a linear stylistic development from baroque to classical, instead discovering composers trying out different options, which might themselves become norms against which new experiments could be made. SIMON McVEIGH is Professor of Music, Goldsmiths College, University of London; JEHOASH HIRSHBERG is Professor in the Musicology Department, Hebrew University of Jerusalem.