This paper describes the usefulness of commercially available thermoelectric modules for building systems that control the temperature of experimental samples. It discusses how such ‘‘solid-state heat pumps’’ can be incorporated into temperature servomechanisms whose behavior can be fully modeled and predicted. It is shown that quite modest systems can offer temperature control over the range 230–330 K, and that milliKelvin temperature stability can be obtained. Finally, in showing that servomechanisms of interest can be modeled by very familiar differential equations, this paper also provides a tutorial introduction to servomechanisms in general.