Lack of multi-dimensional, substantive research on city park systems has undermined the potential role of these public amenities in advancing urban sustainability goals. This study informs holistic policy, planning, and management of parks to balance the multiple goals of sustainability region-wide. A vision for a sustainable urban park system is introduced, informed by multidisciplinary thought and theory. This vision is then operationalized in the development of a quantitative method that examines four key dimensions of sustainability—physical, environmental, socio-economic, and built—across a citywide urban park system. The approach can be customized for use in other cities, but is here applied to Phoenix, Arizona as a proof of concept. Findings demonstrate how a multi-dimensional analysis of an urban park system can provide a more nuanced understanding of these complex human-environment systems, and provide a point of departure for sustainable urban park management and policy as well as future research concerned with balancing multiple sustainability goals in park planning and design.