Measurement of behavior in media psychology is concerned with the question of how media exposure affects individuals' behavioral patterns. Behavior is defined as an occurrence that emanates from a media user and that can be detected on the outside of an individual by an observer. Four central pillars that are key to the observation of behavior are outlined in this entry: the observer, the observation situation, the observation procedure, and the observed individual. Current approaches to the measurement of behavior in media psychology are also outlined.