perform one or more essential activities, requires some kind of assistive device, or needs assistance from another person to perform basic tasks.
Census data from 1994-1995 indicate that about 21 percent of the U.S. population has some form of disability, and that among the 84 mil lion infants, children, and youth ages 0 to 21, 10 percent (8.4 million)— mostly those ages 6 to 14—have a disability. Census data also indicate that among children ages 0 to 14, 1 percent have a severe disability.
Children and youth with emotional and behavioral problems that require residential treatment are a burgeoning population in the United States. Current estimates from the U.S. Department of Health and Human Services (1999) indicate that some 77,200 children and youth reside in psychiatric settings and group homes in this country and that an additional 70 million children and youth are in out-of-home care, including foster care and kinship care. Medical conditions requiring health care have been identified in 60 percent of children placed in foster care; children placed in care due to neglect have the greatest number of medical problems.
On the basis of an analysis of the 1994 National Health Interview Survey-Disability Supplement (NHIS-DS), LaPlante and Carlson (1996) have estimated that 2 percent of the U.S. population has mental retardation or a developmental disability. This is known to be an underestimate, since these data do not include people in institutions, the correctional system, or the military. According to the Arc of the United States—an advocacy organization formerly called Association for Retarded Citizens of the United States—a review of a number of prevalence studies indicates that 2.5 to 3 percent of the general population has mental retardation or a developmental disability (Batshaw, 1997). Applying Batshaw's percentages to the 1990 census of the general population, the Arc of the United States estimates that 6 to 8 million people nationwide have mental retardation (Arc of the United States, 1998).
Because of the different definitions of disability, the population with disabilities is difficult to identify, and their victimization is difficult to measure. Different conceptual models have been proposed to understand disability in a variety of domains, especially health, education, and employment. Some of these explanatory paradigms describe disability as a personal problem caused directly by disease or trauma, and for which treatment or a