The California Thoracic Society (CTS) is the professional society committed in its mission to improve California lung health and, through advocacy and education, advance the science and practice of pulmonary and critical care medicine. It is the largest Chapter of the American Thoracic Society (ATS).

In addition, CTS is a specialty society officially recognized by the California Medical Association (CMA). This provides direct CTS representation on the CMA Scientific Committee on Chest Diseases, its Council on Legislation, and its governing body, the House of Delegates.