This paper presents a model which explains per capita regional product as a function of spatial and non spatial variables. Spatial variables may act within and beyond its territory and are related to spatial phenomena such as spatial external economies or expenditure urban multipliers. The model is estimated using Spatial Econometrics techniques and empirical evidence from the Spanish provinces, «comarcas» (sub-regions) and municipalities. The results validate the model in the three different levels of spatial aggregation and underline that spatial variables explain from 30 to 50% of regional product generation.