This article reviews recent advances in telemetrics, a class of wireless information systems technology that can collect and transmit a wide variety of behavioral and environmental data remotely. Telemetrics include wearable computers that weave on-body sensors into articles of clothing, ubiquitous computers that embed sensors and transmitters seamlessly into the environment, and handheld devices, such as mobile phones and personal digital assistants, that can record cognitive and affective states. Examples of telemetric applications are provided to illustrate how this technology has been used in the behavioral sciences to unobtrusively and repeatedly gather physiological, behavioral, environmental, cognitive, and affective data in natural settings. Special issues relating to privacy and confidentiality, practical considerations, and statistical and measurement challenges when telemetrics are used are also discussed.