I examined the multiple visions of the future of the city that can emerge when city actors and organizations reconfigure themselves to address sustainability. In various cities worldwide, novel ideas, initiatives, and networks are emerging in governance to address social and ecological conditions in urban areas. However, cities can be contested spaces, bringing a plurality of actors, network configurations, preferences, and knowledge that shape the politics over desirable pathways for future development. I used the knowledge-action systems analysis (KASA) approach to examine the frames and knowledge systems influencing how different actors involved in the land governance network of the city of San Juan constructed visions for the future of the city. Results revealed four visions for the city coexisting in San Juan. Although sustainability is a goal that cuts across all four visions, they each optimized distinct dimensions of the concept. The contrasts in visions can be explained in part by competing frames of the urban social-ecological system and power asymmetries in the multiple knowledge systems coexisting in the city. I discussed the theoretical, methodological, and practical implications of the politics of sustainability for adaptive urban governance research and practice. The KASA approach can serve as a window into the adaptive capacity of the city by disentangling the competing ways that actors ‘see’ and ‘know’ the urban social-ecological systems. Most importantly, this approach offers a way of appraising sustainable pathways by revealing either the extent to which dominant social structures and cognitive patterns are being reinforced, or whether opportunities for innovative and transformative approaches are emerging in the city.