The relationship between adolescent personality and problem behaviour has been well established. However, relatively little attention has been given to the role of the social environment in the association between adolescent personality and problem behaviour. We tested the mediating and moderating role of the quality of the parent–adolescent relationship in the associations between adolescents' personality traits and problem behaviour. The sample consisted of 140 adolescents (11 to 18 years of age) and both their parents. Results supported a mediating role of the father/mother–adolescent relationship in the associations between Agreeableness, Emotional Stability, and Conscientiousness and externalizing problem behaviour. The father/mother–adolescent relationships did not mediate the associations between personality traits and internalizing problem behaviour. We also found support for a moderating role of the father/mother–adolescent relationships in the association between Emotional Stability and both externalizing and internalizing problem behaviours. Other moderated effects were specific for parent, personality trait and type of problem behaviour. Copyright © 2006 John Wiley & Sons, Ltd.