The aim of this paper is to quantify the effects of technological external economies over regional labour productivity, whith these effects being obtained in both the short and long run periods. The analysis is carried out from a sectoral and temporal perspective, with the technological externalities being measured by sectoral and regional specialisation and diversity indexes. The dynamic panel data approach used in this paper allows us to consider a sectoral, regional and temporal dimension of the problem. Moreover, hypothesis testing assures the consistentcy and efficiency of the estimated parameters, under simultaneity and autocorrelation problems. The results obtained point to external economies, as one of the sources of the unequal sectoral productivity growth among Spanish regions.

Key words: regional inequalities, sectoral productivity, external economies and dynamic panel data approach.
JEL classification: R11, C33.