Most social interactions involve spontaneous or unintentional behavior. Deliberate behavior, however, represents intentional action. An individual may display a particular emotion or behave in a systematic fashion to convey or conceal a specific type of affect. Often, an observer will question the authenticity of a behavior sequence, deciding whether it is spontaneous or deliberate. This report examines the cognitive basis underlying this discrimination. Thirty-six observers viewed a sequence of nonverbal behavior that was described as being either spontaneous (the stimulus person was filmed with a hidden camera) or deliberate (the person was acting). While watching the videotape, observers segmented behavior into meaningful units. Results indicated that observers who believed that they were watching deliberate behavior generated approximately twice as many units for the nonverbal sequence as compared to observers who believed that they were viewing spontaneous action. The findings are discussed in terms of a cognitive schema that an observer uses in the active organization of behavioral events. (Authors/CJ)