New Caledonia and Reunion Island are French overseas territories, respectively situated in the Pacific Ocean and the Indian Ocean. They both are biodiversity hot spots, but are also agricultural, pastoral and forestry areas. To preserve their environments against the impacts of biological invasions resulting from very diverse taxa (vertebrates, insects, plants, pathogens), these two overseas territories must develop and promote appropriate methods (prevention of new introductions, early detection and eradication, and control or eradication of established species). The research activities of CIRAD, University of la Reunion and IAC contribute to these decision processes, by improving the hierarchical classification of invasive species according to their impacts, by improving the understanding of underlying ecological processes, and by proposing innovative intervention and management methods. This approach for invasive species control in tropical insular areas could also be appropriate in the Caribbean environment.