This paper considers the need for the profession of educational psychology to critically consider the theoretical foundations of expert practice in the wake of the complexities and changes of contemporary society within the UK. It argues that the a priori assumptions of conventional educational psychology practice have led to practice being understood in narrow, instrumental and often asocial ways. The paper concludes that it is now time for educational psychology practice to be primarily viewed as a social and ethical endeavour with a central concern for social relationships and that we need consequently to critically scrutinise the ontological and epistemological basis of our practice and the associated methodological implications. It suggests that a social constructionist epistemology of practice, embracing postmodern themes, may offer a new and useful conceptual constellation for guiding the professional work of educational psychologists.