1 All networks are made of two basic building blocks: nodes and ties. The structure of a network is determined by the distribution of ties among the nodes. Hence, structural change is fundamentally a function of modifications in either the ties or the nodes. Yet in the literature on interfirm networks, structural change has been conceptualized almost exclusively as the consequence of changes in ties. Most studies focus on how tie additions alter networks, such as firms establishing alliances or making joint investments (e.g. Ahuja, Soda, & Zaheer, 2012; Gulati & Gargiulo, 1999; Sytch & Tatarynowicz, 2014). Some work has also considered how tie deletions, such as firms ending alliances, modify networks (e.g. Hernandez, Sanders, & Tuschke, 2015; Polidoro, Ahuja, & Mitchell, 2011). The idea that network change can also be the result of alterations in the nodes is virtually missing from research on interfirm networks (with a few exceptions we note later).