Abstract Broadly speaking, the balance-of-payments constraint hypothesis has been empirically supported. Yet, it shows some shortcomings highlighted in the literature. In our opinion, two of them must be analysed. First, temporary disequilibria and capital flows must be incorporated into the balance-ofpayments constrained growth models. Second, the role of relative prices must be made explicit, since it can be relevant even in an external constraint framework. This study is aimed at developing a model that incorporates both possibilities: temporary external disequilibria and the impact of relative prices. This model is subsequently used to analyse the evolution of the Spanish and Portuguese economies in last decades, and, in particular, the different paths shown by both countries since their accession to the Eurozone. JEL: E12, F41, F4