Atherosclerosis is an inflammatory disease of the arterial wall where both innate and adaptive T-cell-driven immunoinflammatory responses contribute to disease development. Recent studies from several groups suggest that subtypes of T cells, called regulatory T cells, previously shown to maintain immunologic tolerance, control the development and progression of atherosclerosis. Here, we summarize the current knowledge on the regulatory T-cell response in the context of atherosclerosis and the accumulating evidence for its central role in counteracting disease initiation and progression.