The literature is still undecided on whether sub-state elections conform more to a national or regional logic of voting. In this article, I argue that the impact of national politics on regional elections is contingent upon the level of decentralization. I hypothesize that the greater the number of policy areas and resources in the hands of regional governments, the lesser the influence of national coat-tails on regional elections. Using the electoral results of the Spanish Socialist Party in national and regional elections from 1979 to 2009, the empirical analysis shows that regional politicians’ electoral performance is correlated to that of their national counterparts. However, this correlation has weakened as regional governments have gained greater decision-making and financing powers. This has been particularly evident in elections when the regional branch of the party rules a single-party government and competes against strong regionalist parties.