Over the past two decades, tremendous progress has been made in defining and measuring health-related quality of life (HRQOL) and in recognizing its importance as a health outcome (Palermo et al., 2008; Quittner, Davis, & Modi, 2003). More than 50 years ago, the World Health Organization proposed the first definition of HRQOL as “a state of complete physical, mental, and social well-being, and not merely the absence of disease or infirmity” (World Health Organization [WHO], 1947, p. 29). A consensus definition of HRQOL has now emerged, with agreement that it is multidimensional and includes four core domains: (1) disease state and physical symptoms, (2) functional status (e.g., performing daily activities), (3) psychological and emotional functioning, and (4) social functioning (Hays, 2005; Rothman et al., 2007).