Various disciplines have examined the role of urban green space in delivering a wide array of social-ecological values to urban residents. This semi-systematic review of 50 studies assesses how links between the social and ecological qualities of urban green space have been measured to establish social-ecological values, and what qualities researchers have used to define green space type. Our review identified that differences in the definition and measurement of green space and its ecological and social qualities can have a profound impact on interpretations of green space value. We argue that it is critical to acknowledge the heterogeneity among different green space types, and to use suitable metrics of green space ecological and social quality accordingly. We present a heterarchical typology of green space qualities(rather than a hierarchical typology of urban green spaces) that can be used to define green space type and identify research clusters, gaps and emerging lines of inquiry into the social-ecological values of green space.