The territorialization of political competition brought about by decentralization has given rise to a series of cross-regional differences regarding electoral performance, organization and strategies of Spanish state-wide parties. This paper focuses on the motivations state-wide parties have to engage in coalition governments at the sub-state level and the strategies these agreements serve for both regional and federal politics. To do so we will examine all sub-state coalition governments integrated by state-wide parties, either as senior or minor partners, from 1984 to 2011 – which up to 2007 had represented about a third of all regional governments. We will also take into account issues of congruence across levels of government and issues of vertical integration within parties, as well as the relationship of state-wide parties with their sister non state-wide parties (PP-UPN, IU-ICV and PSOE-PSC). The analysis will apply an inductive approach in order to systematize when, why and under what conditions state-wide parties engage in sub-state coalitions. As the participation of IU in coalition governments is quite recent and it has been quite infrequent the paper primarily concentrates on the PSOE and the PP.