This study examined the effects of self-monitoring and rehearsal on the ability of observers to detect deception and on the behavioral correlates of deception. It was hypothesized that observers would be more accurate at detecting deception perpetrated by low self-monitors than by high self-monitors, with the difference particularly pronounced when messages were rehearsed. In addition, low self-monitors communicating spontaneously were expected to display greater rates of verbal and nonverbal responding than high self-monitors who planned their communications. Sixteen high and low self-monitors both lied and told the truth (either spontaneously or after 20-minute rehearsals) regarding their feelings while viewing slides of pleasant landscapes and of disfigured burn victims. Analysis of the responses of the 151 observers who made veracity judgments supported the hypothesis concerning accuracy of deception detection. Coding of 10 verbal and nonverbal behaviors revealed that unrehearsed low self-monitors displayed significantly greater pause and nonfluency rates than rehearsed high self-monitors. Additional findings are reported regarding the effects of self-monitoring, rehearsal, and truthful versus deceptive communication on the behavioral correlates of deception.