Support for independence from Spain has sharply increased in recent years in Catalonia. According to all available evidence, public opinion has shifted from an overwhelmingly pro-autonomy position to an increasingly pro-independence stance. How can we explain such widespread support for secession in a democratic context? Traditionally, national identity has been regarded as the main explanatory factor, but recent accounts tend to underline the effect of political elite’s agency as well as instrumental calculations regarding the economic consequences of secession. However, the identification of this last causal effect is subject to a fundamental challenge: the possibility that economic expectations are mere rationalizations of prior preferences. In order to overcome this identification problem, we combine the analysis of observational survey data with an original survey-embedded experiment that provides a robust test of the causal nature of economic expectations. Our results show how identity, as well as partisanship, are the main drivers of support for secession, but also that economic considerations play an independent role. Results show that economic motivations are more relevant for citizens with ambivalent identity positions and for those that have no party identification, or are partisans of parties with less clear-cut stances on the issue.