Why do only some newly launched rebel groups go on to become viable? This chapter examines all sixteen groups I identified as forming in Uganda since 1986, showing that only those that formed in ethnically homogeneous areas became viable. It then turns to two paired comparisons of rebel groups to understand the mechanisms behind this correlation. Examining why only one group in each pair became viable provides support for several of this book’s key claims about rebels’ rumors better influencing civilian perceptions when kinship networks have certain structures and explains the relationship between those structures and local ethnic demography. In doing so, this chapter shows the inner workings of rebel–civilian interactions at the dawn of a new rebel group forming. It also describes evidence from a field experiment that offers useful support about the role of kinship networks in spreading rebels’ rumors and distinguishes these mechanisms linking ethnicity to rebellion via local networks from those that link ethnicity to rebellion via grievances.