Birds calling and communicating through the din of traffic, pollinators thriving on green roofs, trees sprouting in gutters, flowers blooming in the sidewalk crevices, and earthworms living in sewer pipes. How do they do it? Cities are understudied novel ecosystems of the Anthropocene. Distinct features of urban environments compared to non-built environments are recognized to include distinct soils and altered hydrology, impervious surfaces, heat island effects, altered disturbance regimes that often result in perpetual disequilibrium, fragmentation, light and noise pollution, increased contact with non-native species, habitat fragmentation and loss of coevolved species such as pollinators and seed dispersers. How organisms in cities are responding to these features is less well understood. There is, for example, emerging evidence that many urban ecosystems are in the process of “self-assembly”, with urban organisms rapidly adapting to each other via behavioral, physiological, and genetic mechanisms. In a sense, this is an urban version of the “invasional meltdown” of the invasion literature whereby organisms interact to create niches for themselves and other species. Perhaps this is an inevitable outcome of human activity which is largely focused on human niche creation, an activity that is perhaps most pronounced in our intensively urbanized habitats. Speakers in this symposium will address what is known, and what yet needs to be known, about 1) adaptations (i.e., genetic changes) brought about by selective forces acting specifically in urban ecosystems and 2) responses (i.e., natural/life history shifts that may or may not include adaption), such as changes in diet in response to altered resource bases, that allow living things to survive in cities.