A growing number of environmental educators have become interested in urban environmental education practice – in practice that is specifically tailored to the unique needs and characteristics of urban social-ecological systems. A clear conceptualization of the defining characteristics of healthy urban social-ecological systems can make an important contribution to urban environmental education programs. We synthesized urban environmental educators’ perspectives about the nature of healthy urban social-ecological systems and assessed the implications of those system characteristics for urban environmental education practice. We identified 14 different characteristics needed for urban environments to be healthy. These characteristics demonstrate that, from the perspective of urban environmental educators, the social components of healthy urban systems are equally important to the biophysical components, and these components have profound effects on each other. Through their practice, urban environmental educators cultivate awareness, appreciation, and willingness to act on behalf of both the social and biophysical components of urban systems.