Although it is now well-known that invasive species can have significant ecological effects, it is often assumed that if an invader has documented impacts in one location then the species will have equally negative (or positive) impacts elsewhere. At the same time, there is at least a conceptual recognition that the ecological impacts of invaders vary according to local environmental conditions and the ecological community with which they interact. The type and degree of differences in ecological impacts, however, is rarely empirically demonstrated. There is also growing recognition that we are largely ignorant of long-term ecological effects of invasive species, even to the extent of not fully understanding how persistent initially observed negative effects may be. We posit that the assumption that an invaders’ ecological effects can be adequately characterized based on information from one or a few ecosystems or locations and from studies that cover only a short time frame requires critical evaluation. This symposium brings together ecologists that have collected unique empirical datasets on the spatial and temporal patterns in the ecological effects of invasive species, or have developed conceptual models and standardized metrics of impacts, and challenges them to consider how we may develop a general theory of invasive species ecological effects. As a group, the participants bring research experience across biological realms and taxa, and each brings a unique perspective in the nexus between ecological research and environmental policy. The presentations and end-of-session discussion will identify gaps in data collection, conceptual understanding, and modelling that should be addressed to more fully explain and predict spatial and temporal patterns in invasive species impacts.