A variety of basic institutional changes, in structure, objective and means, have occurred in almost all of the domestic U.S. organizations connected with nuclear energy since the accident at TMI. This paper inquires into some of the apparent driving forces for change, the rates and directions of change evident, and some of the institutional inertias which resist changes (whether needed or unneeded). The basic institutions considered include: 1. (1) Utility industry organizations and working groups. 2. (2) Individual utilities organizations. 3. (3) Domestic reactor supplier industry and second tier suppliers. 4. (4) Materials supply industry including fuel and construction materials. 5. (5) The Nuclear Regulatory Commission. 6. (6) Other government agencies and legislative bodies. A general observation is that most utilities and commercial organizations responded to the evident and implicit lessons of the TMI accident with relatively rapid institutional changes in objectives, organization and resources. For a variety of institutional inertias, the degree of accomplishment of some of the changed objectives cannot be fully assessed as yet, although excellent progress appears evident in some areas. The changes in government institutions have been slower in coming. Generally government agencies intensified the same patterns of activities which were in force prior to the accident. Some of these activities were criticized by the President's Commission (Kemeny Commission) and the Rogovin Report. More recently, the NRC is undergoing substantial changes in institutional approach and structure, but the effects are yet too early to discern beyond a few instances. Related government agencies, including DOE, EPA, and FEMA have not undergone significant change, with the possible exception of FEMA which provides considerable leadership in some areas of emergency response management. Legislative action has attempted significant changes with constructive intent, but limited impact to date.