The performance of a control system is often limited by constraints on timing, bandwidth, and energy. This dissertation explores the trade-offs between constraints on these resources, the control system performance, and the system to be controlled.We begin by considering a networked control system in which the sensor sends its measurements to the controller over a limited-bandwidth communications channel. We explore the observation that the absence of communication nevertheless conveys information --- i.e., nothing communication-worthy occurred. This suggests that energy (or other resources consumed by communication) could be saved using the timing of messages to transmit information, rather than the normal practice of transmitting data in the messages themselves. We develop a framework to explore this idea and derive a condition for the existence of a stabilizing controller that captures the trade-off between bandwidth, resource consumption, and the unstable eigenvalues of the linear system to be controlled. A surprising result is that if this condition is satisfied, then one may design a stabilizing controller that consumes resources at an arbitrarily small rate, provided one has access to a sufficiently precise clock. In an extreme example, a large amount of data is encoded into the precise transmission time of a single bit, and the receiver decodes this data from the time the bit is received. This result quantifies the trade-off between bandwidth and time as resources for transmitting information.Next, we use our framework to analyze a family of event-based controllers. We show that these controllers can stabilize a system while consuming resources at a rate that is within 2.5 times the theoretically-minimum rate. These event-based controllers are intuitive and easy to implement, and our stability condition quantifies the cost (in additional required communication resources) that a control engineer pays for the convenience of implementing an event-based controll