Most urban ecology in cities remains an "ecology in cities" rather than an "ecology of cities." Accomplishing the latter requires the inclusion of humans within the concept of "ecosystem," both how humans alter the properties of urban ecosystems and how these alterations in turn influence human well-being. These influences are both direct (e.g., physiological and psychological influences on the human organism) and indirect, by influencing ecosystem sustainability. For the 2007 ESA meeting, Larry Baker, Loren Byrne, Jason Walker, and Alex Felson organized a symposium to address the relationships among human choices and urban ecosystems. In the introductory talk of this symposium, these authors discussed how the cumulative effect of individual household choices can have major effects on the properties of urban ecosystems.