One of many ARC sites. It's a bit hard to sort them out locally. ARC was once an acronym, now it's word:
In 1990, seven metro ARC chapters, led by a strong group of self-advocates and families, agreed to do away with the name "Association for Retarded Citizens" and its acronym and change their names to Arc. The name change arose out of concern with the label "retarded," and the reference to disability before the reference to personhood. The acronym no longer represented any words, but kept the identity associated with this historic, national movement. The national organization adopted this concept and changed its name to "The Arc" one year later.At one time ARC was the association of retarded children, then retarded citizens.