Supervision is fundamental to the social work profession. However, increasing concern has been expressed over the managerial capture of local authority social work and the use of supervision as a way of enabling management oversight (or surveillance) of practice. Despite the importance of supervision, we have little evidence about what happens when managers and child and family social workers meet to discuss casework and less about how supervision influences practice. In this study, 34 supervision case discussions were recorded. Detailed descriptions are given of what happens in supervision. Overall, case discussions operated primarily as a mechanism for management oversight and provided limited opportunity for reflection, emotional support or critical thinking. With reference to organizational context, it is suggested that these deficits result from a system that focuses too much on ‘what and when’ things happen and not enough on ‘how and why’.