A hypothesis relating personality types to activity of the Behavioural Approach System (BAS) and the Behavioural Inhibition System (BIS) was tested in a sample of 1015 10-18-year-old adolescents. According to this hypothesis, Undercontrollers could be characterized as individuals with overactive BAS, Overcontrollers as individuals with overactive BIS, and Resilients as individuals with low activity of both systems. These predictions were generally confirmed. Psychometrically measured BAS and BIS appeared to be the strongest predictors of Undercontrolled and Overcontrolled prototypes, respectively. Resilients were characterized by low scores on both dimensions.