Nir Hacohen, a faculty member at the Ó³»´«Ã½ and Massachusetts General Hospital, offers a preview of his 2011 Midsummer Nights' Science lecture. The scientific community has learned a lot about immunity, developing vaccines against diseases like polio, measles, mumps, rubella, and more, but many important challenges remain such as making HIV, malaria, and TB vaccines, and eventually cancer vaccines. One way in which these problems are being addressed at the Ó³»´«Ã½ is by using tools that build on the human genome project, enabling comprehensive analysis of the immune response for the first time in history.