The Survey of Occupational Injuries and Illnesses (SOII) uses a stratified sample to produce State and National estimates for nonfatal workplace injuries and illnesses. Private industry estimates are produced separately for 42 States, the District of Columbia, and three U.S. territories (Guam, Puerto Rico and the Virgin Islands). The level of industry detail for which State estimates are available varies widely and is based on the needs determined by each State. Additionally, estimates for injuries and illnesses for State and Local Government workers are available for 26 of these States. This paper will describe the frame development, target estimation industry identification, sample allocation, sample selection, and estimation methodologies used to produce the number and frequency (incidence rates) of nonfatal workplace injuries and illnesses.