In this article the attempt is made to trace and identify the characteristic features of the formation and development of the genre of concerto for clarinet and orchestra of the composers of the XVIII th century. The concertos for clarinet and orchestra by J. Molter, J. Stamitz, C. Stamitz and W. A. Mozart as the first examples of this genre are chosen as the research material. By the example of these concertos the evolution of instrumentation, concert form, thematic base and the ways of its development are observed, the amount of clarinet usage as a solo instrument by composers is determined as well as the ways of the soloist’s and orchestra’s cooperation.