Written rules in formal organizations are distinctive elements of organizational history; they shape organizational change and are in turn shaped by it. These rules are created, revised, and eliminated in ways that leave historical traces, and they have a visibility and durability that elude non-written rules. They thus provide rich data for an empirical probe into the dynamics of organizational history. This study uses qualitative and quantitative data from the history of a specific organization, Stanford University, to develop speculations about the ways in which written rules change. It contributes both to a theory of rules and to theories of organizational decision-making, change, and learning. Organizations respond to problems and react to internal or external pressures by focusing attention on existing and potential rules. The creation, modification, or elimination of a rule, then, is a response to events in the outside environment (such as new government regulations) or to events within the organization (such as alterations in internal government structures).