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Two experiments measured the cardiovascular responses of fourth- and fifth- grade boys to tasks that were relevant to Type A characteristics. Boys were classified as Type A or Type B by the Adolescent Structured Interview (ASI) and Matthews Youth Test for Health (MYTH). Results showed that ASI and MYTH assessments were significantly and moderately correlated—a finding similar to the association among Type A measures in adulthood. During the competition induced by Experiment 1 tasks, ASI Type As showed greater elevations in heart rate than did Type Bs. During the second game of this experiment, the more extreme the Type A behavior, the greater the elevation in systolic and diastolic blood pressure. In contrast, MYTH Type As exhibited enhanced systolic blood pressure in response to the difficult, frustrating, and slow-paced tasks presented in Experiment 2. They also increased in heart rate with increasing exposure to the tasks. These results resemble the findings from the adult Type A psychophysiologic studies and suggest that the cardiovascular responses associated with the Type A pattern may begin in childhood.