Nothing is more difficult for the parents of autistic children to tolerate than self-injurious and assaultive behavior (SIB/A). SIB/A behaviors are unpleasant to observe, to think about, or to discuss, but they do exist, and must be dealt with. Some autistic children hit their heads against walls or floors so hard that they have fractured their skulls, detached their retinas, or caused deafness. Others hit themselves with their fists or their knees so hard that they have broken noses, deformed ears, and even blinded themselves. Some children bite themselves and others, and hit other children and their parents with such violence they have broken bones.