Although the consensus view is that Agreeableness originates from childhood difficultness and regulatory deficits, few studies have investigated such assumptions longitudinally. In this study, we examined this issue by assessing enduring and mediating effects of self-regulation as well as the impact of parenting behaviors on the development of Agreeableness from preschool to late adolescence. Longitudinal data from 965 Norwegian families following children from 1.5 years to 16.5 years were used. Path analyses revealed childhood difficultness at age 4 to be related to Agreeableness at age 16.5; this effect was mediated through emotion regulation in late childhood. However, such mediation effects were primarily found when parents used punitive practices towards their children. Our findings point to personality coherence throughout development. (C) 2016 Elsevier Inc. All rights reserved.