Invasive alien species represent one of the greatest threats to island ecosystems and the unique species that inhabit them. In many instances, eradication or control programs for invasive alien species have effectively curtailed the ongoing loss of biodiversity on islands. Prevention is a more proactive and cost-effective approach, however, and is an emerging global priority in the conservation of island ecosystems. Island biosecurity programs attempt to prevent the introduction and establishment of invasive alien species on islands and dictate actions when an invasive species is detected. Targeted and robust collaboration efforts among the global island community on biosecurity advances and challenges can strengthen and improve local biosecurity programs. In this paper we review the principal tenets of island biosecurity-prevention, detection, and response-using case studies of current island biosecurity programs from New Zealand, Chile, Mexico, the United States, and Canada. Systematic evaluations of biosecurity activities are necessary to ensure that programs are effective and relevant. Key priority actions for the future include strengthening global collaboration on biosecurity through holding annual meetings, sharing resources online, leveraging funding opportunities, and forming working groups that will be engaged in improving critically important but under-resourcal biosecurity programs.