Why are some nascent groups able to organize sustained violent resistance to state repression, whereas others quickly fail? This article links the sustainability of armed resistance to a largely understudied variable—the skills to mount such a resistance. It also argues that the nature of repression experienced by a community creates and shapes these crucial skills. More specifically, the article focuses on a distinction between selective and indiscriminate state repression. Selective repression is more likely to create skilled resisters; indiscriminate repression substantially less so. Thus, large-scale repression that begins at time t has a higher chance of being met with sustained organized resistance at t +1 if among the targeted population there are people who were subject to selective repression at t‒1. The article tests this argument by comparing the trajectories of anti-Nazi Jewish resistance groups in three ghettos during the Holocaust: Minsk, Kraków, and Białystok.