This paper analyses the mechanisms through which capital flows produced financial instability in Spain over a 165-year period. We study why and how capital bonanzas make crises more likely and severe, and whether their incidence varies depending on types of crises (currency, banking and debt crises). We conclude that most of them occurred in different monetary policy regimes, but they were associated with capital bonanzas in a liberal regulatory framework, both of which contributed to a higher likelihood and greater severity of crises. The analysis of the different monetary policy regimes, financial structures and the types of crises allows us to draw some policy implications that emphasise the need for sound financial regulation and supervision.