We evaluated MHC class I‐ and II‐restricted presentation of exogenous antigen by mouse bone marrow‐derived dendritic cells (DC) and splenic B cells. DC presented to class I‐restricted transgenic T cells femtomolar concentrations of antigens from liposomes targeted to the IgG Fc receptor. Targeting these liposomes to surface immunoglobulin did not permit B cells to stimulate class I‐restricted responses. Nevertheless, both DC and B cells presented antigen from liposomes targeted to these same receptors with equivalent efficiency to class II‐restricted T cells. Acquisition of the capacity to present class II‐restricted antigens required shorter periods of differentiation of DC than presentation of exogenous class I‐restricted antigens. The latent period for class I‐restricted presentation of exogenous antigen by DC could not be shortened by exposing them to lipopolysaccharide, double‐stranded RNA or antibody to CD40. Class I presentation depended on expression of the TAP1 transporter. Our data are consistent with the existence of a regulated transport process present in DC which can convey exogenous antigen from endocytic vesicles to the cytosol.