This issue of Biological Invasions represents a collection of papers presented at the Second International Conference on Marine Bioinvasions, held in New Orleans, Louisiana, USA, April 9–11, 2001. The conference offered an opportunity to explore the ongoing marine invasion research and its application to policy and management issues. Many of the questions explored at the conference are universal to invasion science in all ecosystems. Are some habitats more easily invaded than others? Can we predict which organisms will become invasive? What are the impacts of invasive species on ecosystems? Can we use our knowledge to prevent, eradicate, control or manage invasions?