AbstractTimeout has been shown to be an effective procedure in the treatment of aggressive behaviors. Previous research, however, has not provided evidence to support the use of a particular timeout duration in the treatment of aggressive behavior. This study compared the effectiveness of four different timeout durations (1, 5, 10, and 20 min) in the treatment of aggressive behavior in hospitalized children with conduct disorders. Results did not support the use of extended periods of timeout, but suggested that 5 min duration was as or more effective than the other tested durations.