In this paper the effects of quantization in an important class of networked control systems called model-based networked control systems (MB-NCS) are considered. The MB-NCS architecture uses an explicit model of the plant in the controller in order to reduce the network traffic, while attempting to prevent excessive performance degradation. Sufficient stability conditions for two types of static and a dynamic quantization schemes for MB-NCS are derived. An important feature is that the stability conditions are explicitly expressed in terms of the plant and controller dynamics, the error between the model and the plant parameters, the transmission or update times, the quantization parameters, and a robustness measure of the system to parameter uncertainty. This is important because it allows the design of the controller and network parameters to achieve the desired goals. Examples are used throughout to illustrate the main results.