In their 2002 paper on Trait-Based Ecology (TBE), Lavorel and Garnier described the ability to simultaneously predict community changes in response to global change and subsequent changes in ecosystem functions as a “holy grail” for community and ecosystem ecology. While this type of framework could address key questions within these two disciplines, the need for such an approach is even greater if ecology is to provide relevant solutions for preserving, utilizing and sustaining ecosystem services in a changing world. Lavorel and Garnier suggested that a predictive framework could be developed using the traits of organisms. Since the publication of their seminal paper, numerous high profile papers have advocated a TBE approach in both basic and applied ecological fields, and several large research consortiums have invested significant effort in compiling global datasets on the traits of organisms. In many ways, TBE has pushed the field of ecology to a juncture similar to the position of molecular biology at the advent of the sequencing revolution, where sequence data advanced the fields of genomics, proteomics and metabolomics. However, if we are to do the equivalent by using trait data to predict how communities will re-assemble in the face of changing environmental conditions and how these new communities will function to provide necessary ecosystem services, we must critically assess a number of key assumptions and challenges underlying TBE. We have structured the symposium around four key questions that will be addressed by our speakers: 1. Are traits a “fundamental” property of species – i.e. how valuable is information on the mean trait of a species and to what extent is intraspecific variability predictable both within and across species? 2. How should we be measuring and analyzing traits to account for this variability? 3. How do we determine which traits are important for predicting responses to a given driver or effects on a given ecosystem service? 4. How should we scale trait data to predict community response to environmental change and subsequent effects on ecosystem function? We have divided the symposium into three sections. The first addresses the theoretical underpinnings of TBE, the second takes on current challenges to the field, and the final section focuses on attempts to apply the TBE framework to issues of preserving, utilizing, or sustaining Earth’s ecosystems.