The present research investigated psychosocial factors: control beliefs; social relations moderating the SES–health gradient. Participants included 3775 respondents from a national probability sample, Midlife in United States (t1: Age, M = 46.40, SD = 13.00, t2: Age, M = 55.47, SD = 12.43), who provided reports on control beliefs, social relations, and health at two assessment occasions (1994/1995 and 2002/2003). Hierarchical regression demonstrated that control beliefs, social support, and strain uniquely moderated relationships between SES and longitudinal health. The present study highlights the importance of psychosocial factors as protective mechanisms of socioeconomic disadvantages and associated long-term deleterious health outcomes.