T lymphocytes (T cells) comprise a critical component of the immune system charged with diverse functions during an immune response. As a function of maturation in the thymus, T cells become quiescent and remain so until they participate in an immune response in the periphery. Recent work indicates that the control of T cell proliferation is mediated, at least in part, by chromatin architecture. Quiescent T cells possess a condensed chromatin, whereas proliferating T cells have a more open chromatin configuration. The structural maintenance of chromosome (SMC) complexes, which include Cohesin and Condensin, have long been known to play roles in modulating chromatin architecture during cell division; however, they are now known to have additional roles during interphase biology. These roles include the large-scale reorganization of chromatin as well as the regulation of specific gene loci. This review focuses on the roles that SMC complexes play in T cell development and function.