Green space in cities is important, but not always and everywhere for the same reasons. Based on literature review and empirical evidence, we describe transformations in the roles of urban green space (UGS) across time and place using the ecosystem services concept. Urban development and societal change affect the degree of UGS functionality via different trajectories like degradation, revalorization and community action. We explain triggers of different trajectories of change and emerging trade-offs within society. An improved understanding of the shifting roles of UGS can guide urban planning and prioritize designs that fit current and future demand. Research on UGS and ecosystem services should more strongly connect to the development of urban lifestyles in diverse contexts, expose trade-offs between beneficiaries, and explore options for adaptive governance.