What makes some challengers willing and able to embrace a strategy of civil resistance and others not? This chapter shows how social ties–direct interpersonal connections that link members of a challenger organization to other actors in the society–are central to each of these processes. Two types of relationships, what I term “grassroots ties” and “regime ties,” are especially important. Each has distinct implications for different dynamics of challenger-state contention. I develop a typology of challenger networks based on different combinations of these ties, and make predictions about each type of challenger’s likelihood of initiating a campaign to overthrow the regime using a strategy of civil resistance. An attention to challengers’ social ties holds the potential to explain cases that other theories struggle with, such as variation within regional “waves,” within states, or even within movements over time. It can also improve our understanding of how other theoretical mechanisms work by suggesting why some movements might be more vulnerable to repression or fragmentation than others, or how tactical repertoires can evolve.