In 2010, natural and social scientists from the Forest Service's International Institute of Tropical Forestry (IITF) and numerous other local and national institutions came together to form an interdisciplinary research network: the San Juan Urban Long-Term Research Area (ULTRA). This year the San Juan ULTRA published a synthesis of its social-ecological systems research as a special feature in the scientific journal of Ecology and Society. Five key synthesis themes emerged from the research.: (1) The city is subject to multiple vulnerabilities, such as hurricanes and the rise in fossil fuel costs, but socioeconomic factors and education level affect the perception of citizens to those vulnerabilities, even in the face of imminent threat; (2) In light of the social-ecological conditions of the city, how its citizens and institutions deal with knowledge to respond to vulnerabilities becomes critical to the adaptive capacity (ability to recognize, anticipate, and respond to future change) of the city; (3) The relationship between socioeconomic factors and green cover, which in 2002 covered 42 percent of the city, was not what has been reported for other temperate zone cities. In San Juan, neighborhoods with households of high socioeconomic level were not necessarily associated with greater green cover; however, in adjacent neighborhoods within the densely populated zones of the city, households with high socioeconomic level did preserve green cover better than households in lower socioeconomic level neighborhoods. (4) Tropical conditions, such as climate may explain some of the unique aspects of the social-ecological system of San Juan. The most obvious is the exuberance of tropical biota in the city that not only forms novel species assemblages but also provides many benefits derived from ecosystems, including food production for up to 60 percent of the members of particular neighborhoods. Ecosystem resilience, or the ability of ecosystems to withstand disturbances, is particularly high in aquatic and terrestrial ecological systems in San Juan. And (5) it appears that the emergence of novel systems in the city represent adaptive responses to the social end ecological conditions in the city. The study of tropical cities from a social-ecological perspective lags behind the study of temperate cities as in the U.S. and Europe.. Knowledge of tropical cities can help advance the dialogue on how cities function in light of environmental change. As such, tropical cities deserve more social-ecological research through long-term integrated scientific activity that advances both the theory and application of urban social-ecological systems.