Background/Question/Methods: Biological invasions have dramatically altered the natural world and continue to do so, threatening native species and communities and affecting human well being. At the same time, they offer unique opportunities to probe questions such as the nature of range limits and the speed of evolutionary change on unprecedented spatial and temporal scales. Approximately a dozen recent papers have proposed conceptual frameworks for invasion biology of varying degrees of generality, signaling a maturation of the field. Rapid advances in understanding and managing biological invasions depend upon developing a broadly applicable conceptual framework for a discipline that has until recently focused largely on case studies and single factor hypotheses to explain invasions. Invasion biology is clearly ripe for conceptual synthesis and integration. Recently  proposed conceptual frameworks for invasion have not previously been evaluated together. While each offers important advances, there are overlaps among them, points upon which they disagree, and gaps and limitations in what they encompass.
Results/Conclusions: We summarize these recent conceptual frameworks for biological invasions and their predictions, highlight areas of agreement and disagreement, identify gaps, and propose additional factors that have been overlooked that can lead to a broader and more complete understanding of the process of biological invasions. Using examples of globally important invasions, we demonstrate how a synthetic framework can lead to improved explanatory power and precision in the study of invasions, and how in the absence of an adequate conceptual framework, important aspects of invasion biology can be overlooked and predictions can be inaccurate and misleading. The coalescence of these proposed frameworks for biological invasions may resolve longstanding questions, problems and disagreements, and lead to more rapid conceptual and practical progress in the future.