The assessment of children who are ultimately classified as MR has changed dramatically since the period addressed in the previous National Research Council report (1982). Increasingly, a greater percentage of the children come to school already classified by the medical profession, rendering the issue of IQ moot. As MacMillan et al. (1996c) found, most children referred and given psychoeducational assessments and who score below IQ 75 are currently classified in many schools as LD, not MR. The discrepancy between who qualifies as MR according to specified criteria and who is administratively labeled MR by the schools is considerable. This explains, in part, the decline in the number of children identified in school as MR—a phenomenon that is on the way to rendering MR a low-incidence disability.


In 1997, 446,835 students between ages 6 and 21 were receiving services under the category of emotional disturbance (ED). Although the theoretical prevalence estimates for students with ED range from 3 to 6 percent of the student population (Brandenberg et al., 1990; Forness et al., 1983; Skiba et al., 1994), enrollment statistics indicate that approximately 1 percent of the school-age population is certified with ED as a primary disability (Forness, 1992b; see Chapter 2). Furthermore, there is substantial variability in ED prevalence rates from state to state, with estimates ranging from 6 per 10,000 in Mississippi to 2 per 100 in Minnesota (see Table 6-1).

The risk of ED classification for black students is 1.56 percent, a rate that is approximately 1.6 times the white rate of approximately 1.0 percent. The ED classification risk is the same for white and American Indian/ Alaskan Native students. The white risk is approximately 1.4 times the Hispanic rate and 3.6 times the Asian/Pacific Islander rate. The ED risk, like the MR risk, is highest for black students, nearly equal for white and American Indian/Alaskan Native students, slightly lower for Hispanic students, and markedly lower for Asian/Pacific Islander students.

These findings—underidentification of children and youth with emotional disturbances and overrepresentation of black students in the ED category—suggest that relatively few students with behavior problems are being served under the ED category and that the procedures currently employed for identifying and screening students for possible inclusion in this category require examination. Moreover, the lack of definitional clarity and reactive school practices in addressing emotional and behavioral disorders may, in part, contribute to the varying ED prevalence rates and over-representation of black students.

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