This chapter examines how gang members and structure impact survival chances for Rio de Janeiro's gangs. While members provide the foundation for a group's existence, their effectiveness depends on recruitment strategies, role allocation, internal structure, and mobility opportunities. The chapter traces the historical evolution of all these factors in Rio's gangs between the late 1980s and the late 2010s. Despite appearing rigid and top-down, the gangs’ hierarchical structure is actually highly adjustable to local conditions – an adaptation elicited by sustained police repression targeting gang members and leaders. This same repression influenced gangs to become more independent from their own members, with the importance of specific individuals in determining gang survival diminishing over time. Rio's gangs have thus developed resilience through structural adjustability and member substitutability, allowing them to adapt to local contexts and withstand the elimination of their own members and leaders. This transformation reveals how long-term, unplanned changes within urban armed groups can enhance survival prospects even in hostile environments.