This paper applies a social capital perspective to study how business units leverage individuals’ external networks to explore and exploit resources outside the firm’s boundaries. We explore this matter inductively by analysing the development and leveraging of social capital at the business unit level in a global commodity company. Our findings show how individuals’ strong and weak network ties support business unit ambidexterity. We also explore the characteristics of the supportive organisational context that allows firms to reap the benefits of their employees’ external social relationships. This study deepens our understanding of exploration and exploitation at both the individual and business unit levels and contributes to research on contextual ambidexterity.