The present invention provides compositions and systems for delivery of nanocarriers to cells of the immune system. The invention provides vaccine nanocarriers capable of stimulating an immune response in T cells and/or B cells, in some embodiments, comprising at least one immunomodulatory agent, and optionally comprising at last one targeting moiety and optionally at least one immunostimulatory agent. The invention provides pharmaceutical compositions comprising inventive vaccine nanocarriers. The present invention provides methods of designing, manufacturing, and using inventive vaccine nanocarriers and pharmaceutical compositions thereof. The invention provides methods of prophylaxis and/or treatment of diseases, disorders, and conditions comprising administering at least one inventive vaccine nanocarrier to a subject in need thereof.