There is an increasing interest in studying control systems employing multiple sensors and actuators that are geographically distributed. Communication is an important component of these distributed and networked control systems. Hence there is a need to understand the interactions between the control components and the communication components of the distributed system. A recent report on future research directions in control listed understanding control over communication networks as a major challenge for the controls field . Here we present a general framework for examining the communication requirements for networked control. In particular we are interested in the relationship between control performance and communication rate.