PurposeThe aim of this paper is to examine the effect of structural and demographic board diversity as well as board tenure on family firms' environmental performance, by analyzing the differences between family and non-family businesses and within family firms.Design/methodology/approachTobit regressions are applied to investigate the effect of independent directors, CEO non-duality, board gender diversity and board tenure on environmental performance. The study also controls for other board and firm characteristics, as well as for time, industry and country-fixed effects. In doing so, the authors rely on a sample of non-financial listed firms from France, Germany, Italy, Spain and Portugal over the period 2014–2021.FindingsThe authors find that women on the board positively influence environmental performance and this effect is significant only in family firms, although board tenure negatively moderates the relationship. Board independence significantly affects environmental performance only in non-family firms. A strong presence of family directors has a negative effect on family firms' environmental performance, especially when directors' turnover is low.Originality/valueThis paper examines the unexplored relationship between structural board diversity and environmental performance in family companies. This study provides empirical evidence on the association between gender diversity and family firms' environmental performance focusing for the first time on a European setting. Moreover, this study provides evidence of a different effect of board tenure in family and non-family businesses.