The importance of social, emotional, and behavioural (SEB) skills is recognized worldwide, but their measurement has always been a challenge. The BESSI measures 32 SEB skills, divided into five domains (social engagement, cooperation, selfmanagement, emotional resilience, and innovation), but its validity must be expanded to new languages and contexts. Across two studies (N1 = 990, N2 = 824) we developed the Italian version of the BESSI, provided further support for its convergent and discriminant validity with the Big Five, and expanded its nomological network to procrastination, selfefficacy, and emotion regulation. The BESSI-I showed excellent internal reliability and satisfactory fit indices at the facet, domain, and overarching framework level. We also confirmed the correlations between the SEB skills and the Big Five personality traits and found meaningful correlations with the selected external outcomes. Overall, we confirm that the BESSI-I is a valid and useful instrument to assess SEB skills for research and clinical purposes.