The diversity of top management teams is a topic of increasing scholarly and practical interest. It is argued that globalisation requires international operating firms to staff their management teams with international and diverse members. We investigate the influence of institutional environments on gender and internationality diversity in boards to shed light on the question “Why do top management teams look the way they do?” Our sample includes top management team members of the largest stock listed firms in Germany and Poland. The sample consists of 60 firms and 852 individuals from 2019. Our findings suggest that the presence of non-natives and women on corporate boards and the international orientation of board members, in terms of education, work experience and directorships, are attributable to national institutional systems. While Germany´s top managers are becoming increasingly internationally diverse and have increasing gender diversification, the figures for Poland are also increasing, but on a much smaller scale. We argue that country-level institutions play an important role in shaping the diversity of corporate boards. Future research should place more emphasis on the external national environment when investigating board diversity.