The terms are typically used to describe the severity of the disability and are often loosely related to the probability of the disability occurring in the general population. "Mild" is used when there is evidence of difficulty but it is not severe enough to require much, if any intervention. Probably 25% to 30% of the general population could be considered to have a "mild" disability. "Moderate" is the next step up in severity and suggests that the student may need some academic support but would probably not be eligible for special education services. About 10% to 20% of the general student population would fall into this category. "Severe" describes a more significant difficulty which likely would require special education intervention. About 2% to 5% of students would have a "severe" disability. "Profound" refers to the most severe level of disability and would only be expected in about 1% of the general population.