Buying firms must pay increased attention to supply chain sustainability issues, as stakeholders might hold them responsible for non-sustainable supply chain activities. Frequently, sustainability problems occur upstream at the sub-supplier level. Building on the literature on multi-tier supply chains (MSCs), we investigated the sustainability management strategies of buying firms in the food, apparel, packaging, and consumer electronics with regard to second-tier suppliers and beyond. In particular, we analyzed seven cases of global MSCs and found four different characteristic MSC types—open, closed, third party, and “don't bother”. We identified three main factors—supply chain complexity, the sustainability management capabilities of the first-tier supplier, and the type of sustainability in focus (i.e., environmental or social sustainability)—that determine when and how buying firms actually extend their sustainability strategies to their sub-suppliers.