Hafler is a major force in bridging basic immunology, genetics, and neurology deeply probing mechanisms to understand MS. His seminal work in 1985 demonstrating systemic immune involvement in MS (NEJM, 1985) was followed by the first identification of myelin, autoreactive T cells in MS (Nature 1990). In 2004, Hafler was the first to identify human FoxP3 regulatory T cells and then demonstrated that they are defective in MS (JEM, Nature Med, 2011). In 2001, he co-led the international effort that identified the first MS genes outside of MHC (NEJM, 2007) now with over 100 identified genes (Nature 2011). In 2009 Hafler was recruited to become Chairman of Yale Neurology and Professor of Neurology and Immunobiology where he has rapidly built an outstanding clinical program that strongly integrates medical sciences. His scientific leadership has continued where he has deeply examined the function of MS associated risk haplotypes demonstrating their significant biologic effects (JCI 2014), identified NaCl as an environmental cause of of inflammation (Nature 2013), and epigentically fine-mapped MS causal variants discovering the molecular pathways causing MS (Nature 2014). He has received innumerable professional distinctions including being becoming a Jacob Javits Scholar of the NIH, ASCI membership, the ISI most highly cited list, the University of Miami Distinguished Alumni Award and the prestigious John Dystel Prize from the American Academy of Neurology and is a member of the National Academy of Medicine.