The problem of optimal exchange intervention is approached using the techniques derived in the "targets, instruments, and indicators" literature. The optimal exchange-rate policy is one of permitting the appropriate degree of exchange-rate flexibility rather than one of complete fixity or complete flexibility of the exchange rate. Although the problem of the optimal exchange-rate regime has been analyzed in these terms before, criteria previously employed, emphasizing the geographical or functional location of disturbances, are seen to be inappropriate for a portfolio balance model with some degree of capital mobility.