The abuse of people with developmental disabilities has a long and horrific history, which extends from prehistoric to current times. Only in the past 20 or 30 years has society recognized that this abuse is a serious social problem and, with this recognition, research has been carried out on the topic. The limited research that has been done suggests differing causes for making this population so vulnerable to abuse. What is not under dispute is the fact that this abuse continues to this day, both in institutionalized care settings and in family care settings. This manuscript is an attempt to integrate the principal research findings.