stereotypes about people with disabilities that acts as a barrier to keep them from achieving their full potential as equal citizens in society. Among these are beliefs that people with disabilities are inherently unable to manage their own lives, that they are embittered and malevolent, and that they are, by reason of their disability, morally, intellectually, and spiritually inferior to temporarily able-bodied people, or, conversely, that people with disabilities are saintlike, ever cheerful, asexual, childlike, and unusually heroic. Ultimately, it is the belief that people with disabilities are different from "normal" people, and that their lives are inherently less worthwhile than those of people without disabilities. It is the 'ism' at the root of discrimination against people with disabilities on the job, in school, and in the community.
Ableism can be subtle, as when a bus driver radios his dispatcher that he has just picked up 'a wheelchair,' meaning someone who uses a wheelchair for mobility. Or it can be overt, as when a Myrtle Beach, South Carolina motel in 1995 refused to allow two women with cerebral palsy to rent rooms. Pushed to its ultimate extreme it can result in violence as in March 1989 when a group of youths gang-raped a developmentally disabled woman in Glen Ridge, New Jersey. Ableism in Nazi Germany led to the murder of hundreds of thousands of people with disabilities...."
from The ABC-CLIO Companion to The Disability Rights Movement, by Fred Pelka, 1997.
Among the other examples Pelka gives of ableism is this quote from the head of the Spastic Society of Britain, who dismissed the idea that someone with spasticity would ever be able to manage the Society. "That'd be like putting dogs and cats in charge of the Humane Society." Another example I've seen is when people explain that people are disabled because they've sinned, or have bad karma, or their parents have sinned, or God is punishing them for the sins of the entire community. Then there are all those popular culture depictions of people with disabilities as evil, weird, bitter. Think of Dr. Strangelove, Captain Ahab, Captain Hook, etc. It used to be any time you saw someone with a disability in the movies or on TV, he or she was inevitably a villian. These attitudes remain among many people, just under the surface.
Aside from Pelka's books (his latest is, "What We Have Done: An Oral History of the Disability Rights Movement" you might want to check out Joe Shapiro, "No Pity," and the PBS Documentary "Lives Worth Living." There's also a really excellent, though slightly dated documentary "When Billy Broke His Head" that includes a quite excellent introduction to the concept.
Hope this is helpful