The human immune system is a highly evolved system that plays a central role in health and disease. Unders-tanding the aging-associated immune changes is critical to explaining both the disease susceptibility and the different clinical course of rheumatic diseases in the elderly. This is particularly important as the rheumatology discipline is firmly rooted in the era of biologic therapy that is entirely dependent on advances in our knowledge of the immune and inflammatory basis of autoimmune diseases. In this chapter, we briefly review the basic components of the immune system, the recent advances in our understanding of immune senescence, the concept of “inflamm-aging,” and how these age-related changes may be important in determining the health/disease status of the rheumatology patients.