Biological invasion has been one of the hottest topics in ecology in recent years. There has been much progress in understanding the mechanisms of biological invasions and their impacts on ecosystems. At a time of rapid global changes, we are facing new challenges from biological invasions. Here we review recent progress in invasion ecology with respect to invasion mechanisms, the impacts of invasive species on ecosystems and human health, and the responses of invasive species to global changes. We recommend that priorities for future study are the impacts of biological invasions on human health, biological invasions under global change, and invasive species in aquatic ecosystems.