Over the past few years evidence-based practice has become of central concern to health and social services in this country. The fundamental tenant is that there must be a clear link between professional practice and its research base. This paper outlines the concept of evidence-based practice and how it rests on the concept of good quality research--defined as randomised controlled trials. Some of the arguments against evidence practice are outlined; in particular, the importance of educational psychologists' epistemological position. A framework is described that helps to explain how educational psychologists may use their experience to construct explanations for their clients' difficulties. The tension between those educational psychologists who wish to base their professional practice on subjective experience and self-reflection, and those who wish to base it on a more objective base is explored. It is suggested that how this tension is resolved will be the key factor in the continued public and political credibility of the profession. (Contains 7 online resources.)