This chapter aims to describe key facets of the immune system and its relations to adverse social conditions, followed by an exploration of social and immune complexity. By examining the links between social conditions and immune system processes, particularly inflammation, we highlight how these bio-social interactions contribute to health outcome inequities, focusing on Black Americans who bear the brunt of a pervasive racialized social system. This system, inscribed upon bodies in a spectrum of morbidities and mortality risks, interacts closely with the immune system. We reflect on the limitations of current paradigms that often rely on linear methods and theories, which typically make strong assumptions about interdependencies and the functional nature of relationships. In contrast, the components of complex systems exhibit intricate interdependencies, non-linear dynamics, feedback loops, self-organization, and emergent properties. Social structures under systemic racism in the U.S., much like components of the immune system, are interrelated, dynamic, self-reinforcing, and adaptive, showing signs of deep complexity. By balancing current linear paradigms with conceptual and theoretical considerations of complexity, we aim to foster new theoretical insights and methodological innovations. Recognizing the interconnected dynamics of complex systems may inspire transformative policies and interventions, addressing the root causes of health disparities.