Dendritic cells (DCs) orchestrate a repertoire of immune responses that endow resistance to infection and tolerance to self. DC plasticity and subsets are prominent determinants of the quality of elicited immune responses. Different DC subsets display different receptors and surface molecules and express different sets of cytokines/chemokines, all of which lead to distinct immunological outcomes. Recent findings on human DC subsets and their functional specialization have provided insights for the design of novel human vaccines.