We use adaptive cycle theory to improve the understanding of cycles of urban change in the city of Barcelona, Spain, from 1953 to 2016. More specifically, we explore the vulnerabilities and windows of opportunity these cycles of change introduced in the release (Ω) and reorganization (α) phases. In the two recurring cycles of urban change analyzed (before and after 1979), we observe two complementary loops. During the front loop, financial and natural resources are efficiently exploited by homogenous dominant groups (private developers, the bourgeoisie, politicians, technocrats) with the objective of promoting capital accumulation based on private (or private-public partnership) investments. During the back loop, change is catalyzed by heterogeneous urban social networks (neighborhood associations, activists, squatters, cooperatives, nongovernmental organizations) whose objectives are diverse but converge in their discontent with the status quo and their desire for a “common good” that includes social justice, social cohesion, participatory governance, and well-being for all. The heterogeneity of these social networks (shadow groups) fosters learning, experimentation, and social innovation and gives them the flexibility that the front loop’s dominant groups lack to trigger growing pressures for transformation, not only within, but also across spatial and temporal dimensions, promoting panarchy. At the end, the reorganization phase (α) becomes a competition or negotiation between potential directions and outcomes (including conservative leanings and intentional bottom-up change) to restore the former system.