In this paper, we will examine how attachment has become imperative psychological vocabulary in social work. In a case study of social work practice in one Danish municipality, the use of attachment theory shows that the social workers have undeveloped professional insights into attachment theory, yet still use the concept to help comprehend difficult cases. However, their frequent use of the concepts 'attachment' and even 'detachment' appears theoretically arbitrary, and is more reminiscent of psy-culture than strict evidence-based science, and this has a potentially profound impact on how social workers intervene in families.