The conference theme was "new dimensions on old problems," with a different emphasis on each day of the symposium: new dimensions on science, new dimensions on interventions, and new dimensions in the clinic, reflecting the mix of basic science and clinical practice.IAS4 brought together over 130 clinicians and scientists from a broad base of disciplines including physiotherapy, podiatry, biomechanics, orthopaedics, athletic training, and sports physicians. Participants represented many countries, including New Zealand, Brazil, Belgium, Ireland, Great Britain, Denmark, Korea, Iran, Netherlands, Qatar, Canada, and the United States. There was concern about the viability of the conference during the planning of IAS4 because of the global financial crisis and the pandemic of the H1N1 virus. Nevertheless, the number of delegates seemed to be undiminished, resulting in a vibrant, collegial conference.A call for abstracts was initially distributed in mid 2008. Prospective attendees were invited to submit abstracts of work relating to original research, case studies, or clinical commentaries. All submitted abstracts were reviewed for scientific merit by members of the scientific committee. Forty-nine abstracts were accepted and presented at the symposium. The scientific program consisted of 7 invited lectures and 4 workshops from internationally recognized experts and 32 podium and 17 poster presentations of origi- The meeting also provided an opportunity for further development of the work of the International Ankle Consortium, a multidisciplinary group that was formed at IAS2 with the aim of promoting increased harmonization and collaboration in ankle research. A Steering committee was formed, headed by Thomas Kaminski and Jay Hertel, to stimulate the development of the consortium and the future research strategies important to the area. Members of the consortium met to discuss the proposed strategies, future directions, and affirm the proposal to publish a consensus statement on ankle instability.The meeting also accepted a proposal from Virginia Commonwealth University, Richmond, Virginia, to host the Fifth International Ankle Symposium during October 2012.This issue includes a summary statement of the conference, abstracts of the invited lectures and workshops, and the abstracts of the original research presentations, both podium and poster presentations, from IAS4. A nkle sprains continue to be one of the most common sporting injuries but also continue to be the subject of little attention from researchers, largely because of the lack of acknowledgement by funding bodies. Nevertheless, an increasing number of researchers continue in the quest to understand the consequences of ankle sprain, and particularly the resulting instability. Many of the long-held beliefs about the causes of persisting problems have been seriously questioned with the creation of new knowledge.A series of keynote presentations brought this new knowledge to IAS4. Keynote speakers came from a broad crosssection of scientific specialties that ...