This chapter discusses the relationships among disability, the developmental lifespan, and demographic changes. Disability is a complex and multifactorial process, and the results of demographic shifts have occurred more rapidly, been more pervasive, and have been of a longer duration than demographers predicted. Understanding disability-specific response demands, including the emotional adjustment, will provide the foundation to apply traditional theories of human development to IWDs. However, the overriding consideration in applying these theories to IWDs is the acknowledgment that IWDs are normal humans, albeit with a disability.