The relationship of government departments and regulatory agencies to their ‘clientele’ groups in Britain and the United States has received only limited and sporadic scrutiny. The lack of empirical research in this area makes it only reasonable to be somewhat suspicious of the more publicized theories or explanations of the character of public regulation. Such accounts are more confidently offered in the United States, where its tradition of more ‘open government’ allegedly allows the academic observer to see more clearly the manipulation of agencies and departments by powerful interest groups. This article will attempt to show that the excessive emphasis laid on the relationship between regulator and regulated in the United States has hindered the development of a broader understanding of regulatory behaviour. The choice of the term ecology was prompted partly by a desire to emphasize that regulatory agencies can only be fully understood in their widest context. Any explanation which isolates or abstracts them from the regulatory environment is essentially an admission of a failure to grasp the complexities of the relationships and processes involved.