Pulmonary dendritic cells (DCs) constantly sample the tissue and traffic inhaled antigens to the lung-draining lymph node where they normally orchestrate an appropriate immune response. The dynamic ability of these professional antigen-presenting cells to promote tolerance or immunity has been intensively studied by several groups, including ours. Distinct DC subsets in both lymphoid and non-lymphoid tissues have been described based on their surface molecule expression and location. Current efforts to unravel DC development and function are providing insight into the various roles each subset offers the immune system. Elucidating DC functions, particularly in the lung, may then allow use of the inherent ability of these cells for enhanced vaccine strategies and therapeutics for pulmonary infections and diseases.