The Twenty-First Equine Science Society (ESS) Symposium, hosted by Colorado State University, was held May 29–31, 2009, at the Keystone Conference Center in Keystone, Colorado. Over 300 people were in attendance, with representatives from 67 institutions and seven countries. Abstract submissions were up this year, with 123 presentations and 38 posters in areas such as nutrition, exercise physiology, reproduction, production and management, teaching, and extension. Helping to boost this increase was a new section on genetics and a new program that waived registration fees for students submitting abstracts for the graduate student competition. This year also marked a new relationship for ESS as the Journal of Equine Veterinary Science (JEVS) was designated as the official journal of the organization, and the symposium proceedings were published in the May issue of JEVS.