Our model of network mechanisms studies individually addressed message
s between any two members of an organization. For a given organization
al objective function, wt examine communication costs, as measured by
the number of message variables that agents need to exchange at equili
brium in order to achieve the desired action choices. Fur the class of
objective functions we consider. price mechanisms are shown to minimi
ze communication costs. IT cine requires the network tu be hierarchica
l, the organization may be forced to use more message variables. We id
entify the increase in communication tests associated with alternative
hierarchies. (C) 1998 Academic Press.