Exotic invasions provide an unparalleled opportunity for a deeper understanding of the most fundamental question in ecology – what controls the distribution and abundance of organisms? Understanding the mechanisms that enable successful exotics to change from minor components of their native communities to dominants in recipient communities is only possible through biogeographical approaches.The fundamental objective of this proposal is to use a transcontinental approach to study one of Europe’s most noxious plant invaders which originated from North America. By placing a primary emphasis on this novel approach the project encompasses a wide range of cutting-edge research directions that exploit the invasive success of Solidago gigantea. Phenotypic plasticity, genetic background, effects of soil biota and natural enemies, allelopathy, and impact on vegetation will be investigated in the native and in the invaded range. As a result of a multidisciplinary approach important genetic and environmental factors which permit rapid evolution in the case of invasive weeds will be disentangled.This will be one of the first comprehensive field examinations of the behaviour of invasive populations in the native range and non invasive populations in the invaded range. Solidago gigantea and other invasive species are a serious threat for agricultural production, biodiversity and at the same time for human health. The results of the proposed project could provide recommendations for control methods and the applied transcontinental approach of the study can change the viewpoint of future studies with invasive species.