Coactivatorsandcorepressorsregulatetranscriptionbycontrollinginteractionsbetweensequence-specifictranscriptionfactors,thebasaltranscriptionalmachineryandthechromatinenvironment,Thisreviewconsidertheaccessofnuclearandsteroidreceptorstochromatin,theiruseofcorepressorsandcoactivatorstomodifychromatinstructureandtheimplicationsfortranscriptionalcontrol.Theassemblyofspecificnucleoproteinarchitecturesandtargetedhistonemodificationemergeascentralcontrollingelementsforgeneexpression.