Immunosenescence influences many components of the immune system. Most importantly, profound changes in T cell function are evident in older individuals. The impact of aging on specific T cell subsets has been difficult to examine, but recent advances in murine model systems and new insights into T cell function have allowed for the more precise examination of how T cell responses change with aging. Importantly, recent studies have shown that age-related enhancement of both Th17 generation and regulatory T cell function may contribute to significant changes in immune function. In this review, we summarize the current views on how aging influences the factors that impact T cell function and how this can affect the immune response to infections, vaccinations, and tumors.