On page 873, De Berardinis et al. show that bacteriophage can be used to display peptide epitopes capable of inducing both cytotoxic T-cell (CTL) and T-helper cell responses. Previous attempts to prime CTL responses using synthetic peptides recognized by CTLs or T-helper cells have been stymied by poor immunogenicity and antigen processing. In their study, De Berardinis et al. display thousands of copies of a peptide derived from HIV-1 reverse transcriptase (RT2) on the surface of bacteriophage fd. The epitope-displaying phage were able to prime a CTL response specific for the peptide in both human cell lines and mice. The ability to stimulate both arms of the immune system suggests the technique may be useful in vaccination strategies.