The Symphony No. 18 in G major, Hoboken I/18, is a symphony by Joseph Haydn. The composition date is conspicuously uncertain. The Breitkopf catalogue entry assures that it was composed no later than March 1766, the date of the Esterhazy orchestra moving to Esterhaza, but most scholars believe it was composed at least a few years before then. Dates between 1757 and 1764 have been also suggested but not proven.[1][2]