We apply extreme value theory to assess the tail dependence between three currency crises measures and 18 economic indicators commonly used for predicting crises. In our pooled sample of 46 countries in the period 1974-2008, we find that nearly all pairs of variables are asymptotically independent: in the limit, extreme values of economic indicators are not followed by severe currency crashes. Our findings may explain the poor performance of exisiting early warning systems for currency crises. However, we do find that economic variables with stronger extremal association with the exchange rate have better crises prediction performance, both in-sample and out-of-sample.