Ecological, agricultural and economic implications of genetically modified plants on large spatial scales are currently discussed in science, administration, and in the context of agricultural practice. It is still controversial how effects with great spatial extent can be assessed in risk analysis, in the approval procedure, in the planning of co-existence measures, and in post market monitoring. With this volume we present the proceedings of the international conference on «Implications of GM-Crop Cultivation at Large Spatial Scales, GMLS 2008», which provided a platform to collate and discuss available methods, strategies and the state-of-the-art in the relevant disciplines. The conference was held at the University of Bremen, Germany, 2nd to 4th of April 2008.