This chapter explores perhaps the most profound and important empirical question researchers have regarding the psychological and sociological impact of the disability. The terms adjustment, adaptation, reaction, and response are used interchangeably despite the fact they may be different concepts but have overlapping definitions. The chapter first explores people born with a congenital disability, and questions whether such individuals experience any adjustment process as they have no preinjury, nondisabled experience with which to compare their situations. The remainder of the chapter explores the following seven theories of adjustment: stage models (Livneh, 1991), somatopsychology (Lewin, 1935; Trieschmann, 1988; Wright, 1983), the disability centrality model (Bishop, 2005), ecological models (Livneh & Antonak, 1997; Trieschmann, 1988; Vash & Crewe, 2004), recurrent or integrated model (Kendall & Buys, 1998), transactional model of coping (Lazarus & Folkman, 1984b), and chaos theory (Parker, Schaller, & Hansmann, 2003).