This paper addresses growing professional discontents with the increasing formalisation of social work practice exerted through systems of risk management and audit. Drawing on an ESRC-funded study of social work practices in children's statutory services, this paper provides a critique of instrumental approaches to risk management in social work. Through the discussion of three illustrative case examples, we argue that risk management is an inherently complex, contingent and negotiated activity. Social work practitioners are obliged to comply with risk reduction technologies, but informal processes continue to play a critical role in shaping decisions and actions in this relationship-based profession. From practitioner accounts, we identify key elements of the informal logics of risk management. We conclude that the bureaucratic–instrumental bias manifest in the modernisation of children's services, in privileging metrics and administrative power leaves the informal and relational aspects of practice under-emphasised and under-theorised. Suggestions are made about how practice might be advanced in the complex world of child welfare and protection.