Siblings of Adults With Mental Retardation or Mental Illness: Effects on Lifestyle and Psychological Well-Being* Marsha Mailick Seltzer**, Jan S. Greenberg, Marty Wyngaarden Krauss, Rachel M. Gordon, and Katherine Judge Siblings of adults with mental retardation were contrasted with siblings of adults with serious mental illness with respect to (1) the pervasiveness of the impact of the brother or sister on the sibling's life, (2) the closeness of their current relationship and frequency of contact with the brother or sister with the disability, and (3) the factors related to the sibling's level of psychological well-being. It was found that siblings of adults with mental retardation were significantly more likely than siblings of adults with mental illness to perceive that the brother or sister had a pervasive influence on their life decisions and to evaluate their sibling experience as mostly positive. In addition, siblings of adults with mental retardation had a closer relationship with the brother or sister with the disability than siblings of adults with serious mental illness. Finally, siblings of adults with mental retardation had better psychological well-being when they had a close relationship with the brother or sister. In contrast, siblings of adults with serious mental illness had more favorable psychological well-being when they perceived a less pervasive impact of the brother or sister on their life. Implications for future research and service delivery are discussed. Key Words: caregiving, disability, intergenerational relations, mental illness, mental retardation, siblings. There is increasing public recognition that families are the primary source of support for persons with long-term disabilities such as mental retardation and serious mental illness (Francell, Conn, & Gray, 1988; Hatfield & Lefley, 1987; Lefley, 1996; Seltzer & Krauss, 1989). Although the literature on the circumstances of parents who provide lifelong care to a family member with a disability is growing (Cook & Pickett, 1987; Fisher, Benson, & Tessler, 1990; Heller & Factor, 1991, 1993; Lefley, 1987; Seltzer & Krauss, 1994), much less is known about the consequences for adult siblings in these families. With the realization that parental care will ultimately end when the parents die or become incapacitated, it is critical to gain an understanding of the potential role of siblings as the next generation of caregivers. Research on the adult sibling relationship when neither sibling has a disability has demonstrated the unique position occupied by siblings among the range of family relationships. Adult sibling relationships are longer in duration than any other kinship tie (Cicirelli, 1982), are based on a common family life space (Ross & Dalton, 1981), and are egalitarian (Avioli, 1989). These relationships tend to be characterized by supportiveness, concern, and mutual affection (Cicirelli, 1982), although these patterns are affected by gender (Rosenberg, 1982), social class (Brady & Noberini, 1987), and stage of life (Goetting, 1986). There are few systematic investigations of the nature of the relationships between adult siblings when one sibling has a disability, or of the implications of sibling relationships for future caregiving options (Horwitz, 1993a, 1993b; Krauss, Seltzer, Gordon, & Friedman, 1996; Reinhard & Horwitz, 1995; Riebschleger, 1991; Seltzer, Begun, Seltzer, & Krauss, 1991). The available research literature and personal testimonies reveal extremely complex and multifaceted sibling relationships and experiences, which vary across different stages of the life course, and which are colored to a large extent by the milieu of the family (Griffiths & Unger, 1994; Horwitz, Tessler, Fisher, & Gamache, 1992; Stoneman & Berman, 1993). It is also evident that the quality of the relationship between a sibling and his or her brother or sister with a disability is influenced substantially by the meanings attributed by the family regarding the nature of the disability, the reactions of parents to the challenges of the disability, and overall patterns of family adaptation (Begun, 1989; Johnson, 1988; Swados, 1991; Zetlin, 1986). …