Despite many successes in the field of vaccinology over the past century, several important scourges for which effective vaccines remain elusive continue to be threats to public health. The mosquito-borne dengue virus causes millions of infections in tropical and subtropical regions throughout the world, and is responsible for an annual mortality that measures in the thousands. The ubiquitous presence of dengue virus, and its potentially lethal complications, have made the development of an effective vaccine against the virus a priority. However, before such a vaccine can be created, the basic immunology surrounding dengue infection must be clarified. Such research is underway, including efforts focusing on the response of T-cells and the potentially central role of this response in dengue pathophysiology. 'Shaping' the T-cell response may be the key to successful dengue vaccine design.