<p>Systemic lupus erythematosus (SLE) is a chronic, heterogeneous autoimmune disease with a strong female predisposition, characterized by multi-organ inflammation and damage. Its pathogenesis arises from a complex interplay of genetic susceptibility, epigenetic alterations, hormonal influences, and environmental triggers. This confluence drives a sustained loss of self-tolerance and profound immune dysregulation. Innate immune dysfunction, featuring unchecked type I interferon (IFN) production and defective clearance of cellular debris, exposes autoantigens. Concurrent adaptive immune defects include a breakdown of B and T cell tolerance, leading to pathogenic autoantibody production, dysregulated cytokine networks, and aberrant lymphocyte interactions. These processes culminate in tissue injury via immune complex deposition and direct cellular effects. This review synthesizes current understanding of these multifaceted immunological mechanisms in SLE, underscoring how their delineation has informed the development of targeted biologic therapies and highlighting the ongoing need for translational research to improve patient outcomes. Furthermore, emerging insights into the heterogeneity of immune pathways among patients emphasize the potential for personalized treatment approaches tailored to specific molecular profiles.</p>