This paper aims to analyze the determinants of productive agglomerates in the State of Paraná, southern Brazil, mainly focusing on the effects of economies of specialization and diversification. To achieve its aim, ten industrial sectors (the most representative in terms of job offer) were selected and through panel data (using spatial panel), regressions were estimated, one for each industry, considering the 399 towns and the period between 2000 and 2015. The results from all sectors showed statistically significant externalities originated in the productive specialization, affecting positively the dynamics of industrial growth in the Paraná towns. Moreover, in many sectors, a spatial effect was observed, with spillover of the industrialization dynamics to neighboring towns.