The International Union Against Tuberculosis and Lung Disease (The Union) held its 40th World Conference on Lung Health in Cancun, Mexico, between 3 and 7 December 2009. It was attended by over 2000 delegates from 104 countries around the world. The conference featured four stimulating plenary sessions and an extensive selection of scientific symposia. A total of 1125 abstracts were also presented from five broad categories: clinical trials and TB basic science, clinical research for treatment and care, epidemiology, education, advocacy and social issues, and policy and program implementation. In addition, the conference was preceded by a series of well-attended postgraduate courses and workshops.