Search theoretic models of money emphasize monetary exchange as the ou
tcome of economic environments characterized by bilateral trading fric
tions. This paper analyzes the efficiency of monetary exchange in a se
arch model of fiat money where individuals invest costly effort in the
exchange process. Because the optimal effort each individual trader i
nvests in exchange is based upon the private rather than social gains
from trade, decentralized monetary equilibria are shown to be ineffici
ent relative to the social optimum. However, for an appropriate divisi
on of the gains from trade given to buyers and sellers, it is possible
to attain social efficiency. The nature of these search externalities
for monetary exchange and their implications for policy are evaluated
and discussed.