The latent power of social work's position at the centre of welfare services and as a coordinator and definer of social realities can be argued to have led social work to become "the assessment profession". Building upon a critique of the key distinction between "description and prescription", we argue that the conceptualization of assessment needs to be enriched to understand its influence across the different domains of professional education and professional practice in social work. Key perspectives are drawn from the work of two contrasting theorists: the critical social theory of Habermas and the psychological constructivism of George Kelly. Arguments are developed towards a new approach of conducive assessment in social work. (Contains 6 notes.)