Childhood externalizing behaviors and its association with adult personality traits. In the present study we studied the association between the externalizing behaviors in childhood and the personality traits in adulthood, from an ongoing prospective longitudinal design. Personality was defined by the big five factor model. A total of 101 individuals (M = 23.31 years, SD = 2.18), 67 males (66.3%) were evaluated through two measures: the TDAH teacher´s version scale (childhood) and the NEO PI-R personality scale (adulthood). The results showed significant correlations with moderate magnitude between the externalizing behaviors and the Consciousness and Agreeableness traits. The attention deficit correlated negatively with the Conscientiousness trait. The Agreeableness trait correlated negatively with the three dimensions of behavior: attention deficit, hyperactivity/ impulsivity and antisocial behavior. In general, the results indicated significant relationship between externalizing behaviors and personality traits. The stability of these dimensions is discussed.