Cytotoxic T lymphocyte (CTL) induction usually follows processing of antigens via endogenous pathways before presentation on the cell surface in association with MHC class I molecules. Soluble antigens do not, in general, induce specific CTL responses. Here, Syamal Raychaudhuri and John Morrow suggest that a novel adjuvant formulation can elicit CTL responses to soluble antigens and discuss the implications for vaccine development.