The author draws upon Privacy and Freedom (Westin, Athenaeum, 1967) to identify three surveillance techniques: observation, extraction and reproduction, and to discuss the propriety of each as a detection, control or evaluative device in the workplace. Surveillance by extraction, including polygraph testing and personality testing, is condemned as overly invasive and unreliable. Surveillance by reproduction of communications — information secretly gathered by interception of oral communication, whether by wiretap or other means — is arguably inadmissible under federal and state laws regulating such surveillance methods. The least problematic method, surveillance of the workplace by direct or remote observation, may deter misconduct but also may inhibit creative or innovative employee conduct that enhances performance levels.