Urban ecology has quickly become established as a central part of ecological thinking. As cities continue to grow in size and number, two questions serve to unify this broad and multidisciplinary research landscape: (1) how can urban ecology contribute to the science of ecology, and (2) how can urban ecology be applied to make cities more livable and sustainable? In spite of the advances made thus far, there are many unexplored ways of integrating the science and application of urban ecology. Although scientists assess and make predictions regarding the connections between environmental and socioeconomic processes, practitioners involved in real-world application deal with urban planning and with designing ecosystem services to improve living conditions for all urban inhabitants and to make cities more sustainable. Research in urban ecosystems can be developed from many different perspectives, and we suggest that each perspective has something to offer both society and the science of ecology. We present several research perspectives and describe how these can integrate conceptual and applied aspects to bridge the figurative gaps between trees, buildings, and people.