The identification and characterization of epitopes is essential for modern immunologic studies. Here, we describe a novel methodology we have developed to identify T cell epitopes exploiting the phenomenon of cross presentation. Particulate antigens, in the form of beads, are very effective in delivering exogenous antigen to both the class I and class II pathways. We will review our efforts to screen entire genomes of pathogens for T cell epitopes taking advantage of the advances in genomics using Francisella tularensis as a model. By automating aspects of this technology we will be able to functionally screen the entire genome of F. tularensis for T cell epitopes. This technology should be applicable not only to F. tularensis, but also to many other pathogens as well.