Urban popular movements that organize illegal land invasion communities present an intriguing puzzle. When most invasion organizations acquire land titles, their participation levels plummet and their agendas stagnate; yet some neighborhoods achieve land titles, sustain high participation, and acquire other services, such as piped-in water. Why do these organizations achieve movement resilience? The more typical trajectory of movement collapse is explained by the disappearance of the key selective incentive, property security. Some organizations, however, evade this “security trap” through mixed motives: their basic material agenda is supplemented by a nonmaterial and often altruistic agenda, which sustains participation in the face of reduced selective incentives. Examining three neighborhood case studies in Lima and Quito, this article argues that a new, “innovator” type of invasion organization is more likely to exhibit sustained participation and movement resilience due to tactical innovation, democratic governance, and mixed motives.