It used to be that disabled kids were almost universally educated in special classes. Now, most disabled kids are educated in regular classes, often with assistance of some kind. A lot of people appear to be of the opinion that all disabled children should go to regular classes, with or without assistance.
I disagree. Firstly, it's important for many kids to have contact with true peers, which for disabled children are kids with similar disabilities. The importance varies according to disability - for example, Deaf children, who sign but do not speak, are much more socially excluded in classes where most children don't sign very well than in special classes with other Deaf children. Many accounts of conferences for parents of children with rare disabilities - for example distal trisomy 10q - describe how these children, most of whom have no contact with kids like them except for the conference, seem "drawn" to each other.
Secondly, even with special assistance, they often don't get as good an education in disability-specific areas. Mainstreamed blind children, for example, typically receive poorer education in how to navigate using a cane. This problem can be solved while mainstreaming the child, by having the child "pull out" for modified classes. But for many kids, this is a reality.
Also, some of the proposed benefits of mainstreaming and drawbacks of special education are not really very good. Firstly, many people claim that a benefit of mainstreaming is peer pressure to act normal. I doubt anyone who says that has ever been bullied.
A disabled child can't become normal, no matter how hard they try. A few kids can learn to pass for normal, like a gay person being in the closet, but most can't even do that (although most can hide some aspects of the disability). So most disabled kids, if pressured to be normal, will be experienced the stress of expectations they cannot fulfill - and therefore chronic failure, which has been proven to have serious ramifications. And when they fail, their peers have serious punishments - taunts, exclusion, and sometimes physical violence, commonly described as bullying. Numerous children have committed suicide because of bullying, and bullying was implicated in the Columbine shooting and similar incidents. As a survivor of bullying, I can sympathize with those children. Many times I wanted to die, and on one occasion fantasized about turning into a vicious dog and mauling my bullies.
There is the parallel "drawback" of mimicking abnormal behavior in special education students. With the exception of aggression, self-injury, and similar behavior, this is not necessarily a bad thing. One autistic woman described how some autistic people she knows started doing autistic behaviors they hadn't done before and found beneficial effects. Certain coping strategies may be thought up by children with disabilities, if similarly disabled child mimic these, that would be a good thing. Normal children are unlikely to be models of such behavior because they have little need for it.
For a personal example, as a child I liked shiny things, but once I focused on them, the enjoyment went away. Recently, as a teenager, I volunteered with autistic children and met a child who dangled shiny ribbons in front of his face. I tried that, and realized that what I really liked about shiny things was the change caused by changing the viewpoint of the object. As such, I now get more enjoyment out of shiny things.
Additionally, normal behavior isn't always that great. I'd rather any child mimic the empathetic behavior common in kids with Down Syndrome than the cliquish, conformist behavior of normal kids, and especially a disabled child (for the above-stated reason that such behavior would be maladaptive for someone who can't fit in). And I'd rather more children exhibit the truthfulness characteristic of autistic kids, rather than learn to lie habitually. Despite the saying "perfectly normal", normal isn't perfect.
Also, it seems that viewpoint supports discriminating against children who behave oddly, even if there is nothing objectively wrong with doing so. To reinforce views like that certainly does not help disabled kids. Why should a child do a more normal behavior when they prefer a harmless, abnormal behavior, even if they can do it? What is objectively "better", for example, about watching TV rather than lining up cars across the bedroom floor? Some people are of the opinion that because most people don't enjoy staring at shiny things, I should stop doing so. Why aren't people allowed to be different?
Another drawback is poorer quality of education in special classes. Aside from specific things like navigation for blind children, many times normal kids are given better quality education. This is true. But firstly, this can occur in mainstream classes too. My dad was a high school teacher once, and had a student who was a mainstreamed developmentally delayed kid that was not being challenged enough. His teacher aide was giving him the same kind of math problems year after year, even though he'd long since mastered them, because she assumed he would not be able to do harder problems.
Secondly, it doesn't need to be so. One person said "separate-but-equal can never truly be equal" but that is not true. The way it becomes unequal is when one group is viewed as less deserving, less worthwhile than the other one. But if both are viewed as equally wonderful people, with differing needs, then the quality of education could be just as good for both groups. Before this happens, however, we must learn to accept differences without portraying one as better than the other.
In conclusion, mainstreaming is a good choice for some kids, but is not universally better than special education. And special education can be better for some kids. Lastly, in order to truly help educate disabled children properly, we must let go of prejudices that normal is better than abnormal, or that two different groups must be on a hierarchy, with one be