This article surveys recent thinking on the topic of currency unions, separating out and presenting the lessons that apply to the New Zealand context. A decision on joining a currency union is predominantly political, and would probably be accompanied by other complementary measures that also further economic integration. Nevertheless, such a decision has implications for financial markets, the economy in general and the institutional role of the Reserve Bank. For all of these reasons, the Reserve Bank will continue to monitor the literature on the subject, and occasionally contribute to it, in order to facilitate informed debate in New Zealand.