Tens of thousands of workers participated in rescue, recovery, and cleanup activities at the World Trade Center (WTC) site in lower Manhattan after the terrorist attacks on September 11, 2001 (9/11). The collapse of the WTC resulted in the release of a variety of airborne toxicants. To date, respiratory symptoms and diseases have been among the most examined health outcomes in studies of WTC disaster workers. A systematic review of the literature on respiratory health outcomes was undertaken to describe the available information on new onset of respiratory symptoms and diseases among WTC disaster workers after September 11, 2001. Independent risk factors for respiratory health outcomes included being caught in the dust and debris cloud, early arrival at the WTC site, longer duration of work, and delaying mask and respirator use. Methodological challenges in epidemiologic studies of WTC disaster workers involved study design, exposure misclassification, and limited information on potential confounders and effect modifiers. In the 10 years after 9/11, epidemiologic studies of WTC disaster workers have been essential in investigating the respiratory health consequences of WTC exposure. Longitudinal studies along with continued medical surveillance will be vital in understanding the long-term respiratory burden associated with occupational WTC exposure. (Disaster Med Public Health Preparedness. 2011;5:S189–S196)