Small-scale bottom-up urban agriculture (UA) initiatives have a large potentialto improve the quality of life in cities through their impact on ecological andsocial processes. However, it is unclear which criteria determine their successfulestablishment and continuity. We assessed these criteria for 29 projects inthe Netherlands and Switzerland using a vulnerability analysis framework. Weanalyzed biophysical and socio-institutional criteria for project establishment byconducting interviews with project leaders. Projects were scored for their exposureto perturbations and their sensitivity and resilience after a perturbation,resulting in an overall vulnerability score per project. We found that the vulnerabilityof UA systems depends strongly on local circumstances. The main perturbationsand causes of vulnerability originate from social-institutional and humanconditions, such as the institutional sphere, assistance of local authorities, andthe determination of project leaders. Different sources of resilience were found,such as social protest, and project leaders’ adaptation to local circumstances. Biophysicalfactors were of less influence as the adaptive capacity of projects providesresilience against such perturbations. As perturbations are case-specific, targetedpolicies would be desirable to support these promising initiatives.