The aim of this paper is to analyse the impact on firms\u2019 productivity of innovative activities and agglomeration effects among firms belonging to Marshallian industrial districts and the possible joint effect of these two forces.We study a sample of 2,821 firms active in the Italian manufacturing industry in the period 1992\u20131995. Our analysis uses an original data set based on three different Istituto Nazionale di Statistica statistical sources \u2014Community Innovation Survey, Archivio Statistico delle Imprese Attive (Italian Business Register), and Sistema dei Conti delle Imprese (Italian Structural Business Statistics)\u2014to estimate an \u201caugmented\u201d Cobb-Douglas production function to account for the impact of techn...