Mainstreaming vs. Inclusion
In 1975, Public Law 94-142 was established by the Congress. That law required that all children be educated in "the least restrictive environment." It was, essentially, the "special education" law. Out of that law comes the idea of "mainstreaming." "Mainstreaming" means nothing more than moving a child out of both special education self-contained classrooms and pull-out programs and putting him/her in a "regular" classroom -- in the "mainstream" of schooling. (Regular classrooms are considered to be the mainstream.) But, this interpretation of the law works from the idea that the individual child may be better served by not placing him or her in regular classrooms, that some children are better able to learn in more sheltered environments, such as self-contained classrooms. All children who receive this service do so on the basis of both a battery of tests and conferences with educators, psychometrists and parents, which result in an Individual Education Plan (IEP) for the child. These people decide to what extent the child will be in regular classrooms, pull-out programs, and/or self-contained classrooms (parents have absolute veto power). In fact, most special education children spend the majority of their time in regular, or mainstream, classrooms.
Unfortunately, this is a relatively expensive program. Approximately 12% of children in American public schools receive special education services. Something in the neighborhood of 35% of the school's academic budget goes to support it. (I think it important to distinguish between" the academic budget" and "the budget." The academic budget is the part of the budget that actually goes to support classroom operations; it is about 60 - 65% of the total education budget.)
Inclusion is a little more difficult to define exactly, because precisely how it will be worked out varies from program to program. It is not yet widely practiced and, therefore, has numerous variations.
Generally speaking, though, inclusion differs from mainstreaming in that it would pretty much eliminate pull-outs and self-contained classrooms. Special needs children would be "included" in the regular ed. classrooms. These students would still have IEPs, but the efforts to fulfill the IEPs would be made in the regular classrooms, which in perhaps 10% - 20% of the cases is already done. In one manifestation of inclusion, the special education teachers would come into the mainstream classrooms and work with the students in that environment. Thus, there would not be elimination of special education services, but a change in the location of their delivery. The commonly mentioned problem with this approach is that it would either result in attention to fewer students by the same number of special education teachers, less attention to the same number of students by the same number of special education teachers, or the same amount of attention to the same number of students by more special education teachers. One possible way to prevent any of those things happening, of course, is to turn part of the special education responsibility over to the regular classroom teachers. Most regular ed. teachers resist that, of course, because they don't feel they have been adequately trained to deal with special needs children.
I don't want to get into the arguments pro and con. What is important to understand is that these are two different ways of enacting PL 94-142. The key feature of "inclusion" is that it would eliminate, or at least diminish the number of, self-contained (or separate) special education programs and perhaps special ed. pull-outs as well. Special education teachers, rather than teaching in their own classrooms, would come into regular education classrooms and help the special education students in that environment.