This paper is the introduction to a special issue of the journal, Marine Ecology Progress Series, titled "Invasion of Atlantic coastal ecosystems by Pacific lionfish". The issue is a compilation of papers presented at the 2015 special session of the Gulf and Caribbean Fisheries Institute meeting, which was co-organized by REEF and partner organizations. New findings include mechanisms that enhance the success of the invader, the extremely broad and variable diet of invasive lionfish, the ecological effects of the invader on native fish populations in various environmental contexts, and non-consumptive interactions between invasive lionfish and native predators. The entire issue is available online at http://www.int-res.com/abstracts/meps/v558/#theme.