Agriculture represents one of the largest industrial sectors in the United States. In a recent (2002) census of agriculture, it was reported that more than 2.l million farms were active in the United States, with total acreage surpassing 938 million acres (USDA, 2002). Although the majority (about 90%) of farms in the United States are small, family-owned enterprises, commercial farms account for more than 50% of farm production (USDA, 2002). However, these large, commercial farms represent less than one-third of the total acreage used for farming (USDA, 2002). In 2004, the average size of a farm was 443 acres (USDA, 2002). A large portion of the background material for this chapter was adapted from a review by Davis and Kotowski (2007), who focused on ergonomic risks associated with musculoskeletal injury; herein, we discuss how those risks apply to agriculture. Agricultural production in the United States can be divided into two broad categories: animal production (40%) and crop production (60%) (USDOL, 2005). These two categories of farm production present different sets of risk factors for work-related injuries and illnesses. Risk factors in animal production include being struck or stepped on by an animal and performing heavy lifting (e.g., in milking, feeding, transferring, and caring for animals). On the other hand, risk factors for musculoskeletal disorders (MSDs) associated with crop production result from more repetitive activities that often involve extreme bending or stooping, working with the hands and arms in awkward positions, and heavy lifting of agricultural products and equipment. Regardless of the type of production, the majority of workers in this industry are manual laborers (USDOL, 2005). A difficult problem with applying ergonomics to agriculture is that, in comparison with other industrial sectors, the specific exposures are unique; in addition, the tasks and exposures vary by season and type of agricultural production. This variation places farmers and farmworkers at increased risk of injuries and MSDs. Contributing to the uniqueness of risk exposures in agriculture are the special populations within the sector. The U.S. agricultural workforce is dominated by males, most likely because of the physical demands of the work. In addition, however, the industry includes three other at-risk populations of workers: females, children/adolescents, and migrants. Females make up about 30% of the farm workforce and often play an active role in the daily work activities (Oliveira et aI., 1993). They are involved in heavy physical work on the farm and perform many of the same tasks as males. Unfortunately, this role may put them at increased risk of MSDs because they generally have a lower strength capacity than males. Furthermore, agriculture is one of the few industries in which children and adolescents are considered an integral component of the workforce, performing physically demanding jobs that are typically designed for adults. Children and adolescents represent a major segment of the agricultural workforce (Waters, 2002). Researchers estimate that this segment comprises between 1.2 and 3.4 million individuals under 20 years of age (Dacquel and Dahmann, 1993; Schulman et aI., 1997; Myers and Hendricks, 2001). Among these young workers, the predominant age is between 16 and 19 years (53%) (Myers and Hendricks, 2001). Farm youth perform many physically demanding tasks, including lifting and moving materials and equipment, operating farm equipment, and doing jobs requiring moderate to high levels of strength and coordination (Bartels et al., 2000). Few studies, however, have evaluated the physical demands associated with jobs performed by children and adolescents, and even fewer studies have examined the magnitude and severity of risks that these jobs represent for young workers. Moreover, there are no surveillance systems in place to monitor and evaluate the magnitude of risk for this younger population. In addition, there is no scientific information about the potential long-term risk of chronic health problems (such as MSDs or osteoarthritis) that may occur in adulthood resulting from work during childhood. One of the unique populations within the agricultural workforce is migrant workers, who account for a significant percentage (42%) of the crop workers in the United States. These workers are often overlooked with respect to health and safety issues because they travel between regions (often more than 75 miles apart) to meet seasonal farming demands (USDA, 2002). These workers perform many physically demanding jobs that usually involve heavy lifting, awkward postures, and long work hours in poor environments (e.g., heat, rain, and muddy fields). They have limited access to information about reducing exposures and treating health issues. Another major issue with regard to understanding the magnitude of the problem of MSDs in agriculture is the lack of reporting of such incidents. Only 4%-10% of U.S. farms (both family and nonfamily) have more than 11 employees and therefore are subject to reporting requirements of the Occupational Safety and Health Administration (OSHA) for Injuries and illnesses (Aherin et ai., 1990; Purschwitz and Field, 1990; Baker et al., 1992; Waller. 1992; Zhou and Roseman, 1994; NSC. 1997). As a result. because the statistical analyses do not take into account the majority of the exposed population, their findings cannot be considered conclusive (Purschwitz and Field, 1990; Zhou and Roseman. 1994). Musculoskeletal health outcomes for farmers and farmworkers fall under two broad categories: acute injuries occurring during a onetime event and longer-term MSDs resulting from cumulative exposure over time. Acute injuries result from single traumatic events such as slips and falls, kicks by animals, and lacerations; most MSDs likely develop from cumulative or repetitive exposures to a stressor. Although both types of injury have significant ramifications for the long-term health of farmers, there has been much less research on MSDs than on traumatic injuries and fatalities in farming.