Institutional isomorphism has been a major intellectual contribution within institutional theory for three decades. The effects and processes of institutionalization have traditionally focused on stability and persistence of institutions, and more recently on institutional change. This study contributes to the IS field using the lens of coercive, mimetic and normative isomorphism and change within a highly institutionalized organizational field of health care. The setting is the National Health Service in the United Kingdom, where in 2002 a major government policy was launched to introduce Electronic Health Records (EHRs) to over 50 million citizens. Using episodic interviewing techniques and content analysis of government health IT policy documents, this study provides a longitudinal analysis of the introduction of government policy to modernize health care using information technology. Institutional isomorphic conditions become conflicted with attempts to impose field and organizational change. As clinicians attempt to retain their professional dominance in a climate of almost continuous restructuring of health services, political initiatives to implement EHRs are met with resistance from key stakeholders, resulting in policy changes and further delayed implementation times.