This thesis reports on a four-year field study conducted at the Saskatchewan regional office of the Department of Indian Affairs and Northern Development, a large department of the Government of Canada. Over the course of the study, a sweeping government-wide accounting reform took place entitled the Financial Information Strategy. An ethnographic study was conducted that documented the management accounting processes in place at the regional office prior to the Financial Information Strategy reform, the organization’s adoption of the new accounting system associated with this initiative, and the state of the organization’s management accounting system once the implementation was complete. This research, therefore, captures in detail a management accounting change process in a public sector organization. This study employs an interpretive perspective and draws on institution theory as a theoretical framework. The concept of loose coupling and insights from the literature on professions were also employed in the explanation-building process for the case. This research contributes to institution theory and the study of management accounting change by recognizing conflicting institutional forces at the organizational level. An existing Old Institutional Economics-based conceptual framework for management accounting change is advanced and improved upon through the development of a new conceptual framework that incorporates the influence of wider institutional forces, the concepts of open and closed organizational systems and loose coupling, and the recognition of varying rates of change and institutionalization of organizational activity sets. Our understanding of loose coupling is enhanced by the interpretation of institutional influences developed in this study as is the role of professionalization as a normative influence in public sector organizations.