We develop a model to analyze the optimal combination of macroprudential and monetary policies in a small open commodity-exporting economy. Unlike a closed economy, where monetary and macroprudential policies tend to be substitutes, in a small open economy the optimal policy mix depends on the specifics of shocks and economic structure. Monetary and macroprudential policies tend to be complements when the degree of pass-through of credit spreads into marginal costs and prices is sufficiently high, or when a credit boom is caused by a commodity boom, a fraction of consumers lacks access to financial markets, and the government follows a fiscal policy rule. The two policies are substitutes when the complementarity between domestic and imported production inputs is sufficiently high.