Andrew Yates' graduate and early postdoctoral training was in theoretical physics and cosmology, but since the late 1990s he has worked as a quantitative immunologist. His research integrates theoretical and computational tools with more traditional experimental approaches to study the dynamics of lymphocytes, white blood cells that are key components of vertebrate immune systems. His group's aim is to develop a mechanistic understanding of the rules underlying lymphocyte development, homeostasis, and their trajectories in response to infectious challenge. Their philosophy is to confront and break models with data to search for parsimonious, robust and quantitative explanations of immunological phenomena. Currently they focus particularly on the evolution of immune repertoires throughout an individual's lifespan, and their recovery in HIV-infected individuals following antiretroviral therapy.