Lymph nodes (LNs) are the organs where innate immune responses lead to acquired immunity, where some of our most devastating pathogens evade immunity, and where autoreactive lymphocytes first encounter tissue-specific self-antigens and are either tolerized or activated. The many roles of LNs depend on the coordinated migration of its cellular constituents. This article covers new insights into the organization and microvascular specialization of LNs, the guidance mechanisms that allow lymphocytes and antigen-presenting cells to find their correct place in the nodal parenchyma; and the role of afferent lymph flow in LN function.