Colligation in human services is the more or less structured process of selecting and ordering information using relevant theories and concepts to assemble a credible and 'followable' account of a client's situation, according to Andrew Abbott (1984). Through colligation, caseworkers limit complexity in light of professional knowledge, common sense and legal guidance, preparing for a formal classification of the problem. In this article, I argue that studying processes of colligation in child welfare allows for a nuanced exploration of how structural, cultural and individual aspects of professional practice interact when grasping a professional mandate concerning children, parenting and risk.When introduced to a child or a family previously unknown to child welfare services, the caseworker needs to specify the problem at hand. Such a specification involves describing the situation using child welfare vocabulary, and narrowing down the options available for action.Borrowing a term from medicine, Abbott calls this diagnosis, and it involves the two steps of colligation and classification:Colligation is assembly of a 'picture' of the client; it consists largely of rules declaring what kinds of evidence are relevant and irrelevant, valid and invalid, as well as rules specifying the admissible level of ambiguity. Classification means referring the colligated picture to the dictionary of professionally legitimate problems. (Abbott, 1988: 41) While classification is a deductive activity that involves placing items under headings, colligation is an inductive process that involves identifying pieces of information that are relevant to the mapping of a particular professional problem (Abbott, 1984). Cases involving suspected neglect challenge the caseworkers' ability to define the cutting point between adequate and inadequate care in relation to the particular child in need. Out-ofhome placement is a measure of last resort, involving the strongest public intervention into the private lives of families, and there is no partial placement. A child is under the physical custody of either the parents or the child welfare system. Cases that remain on the brink of out-of-home care are described in this article as being on the tipping point between two different logics, and these logics can be understood as binary oppositions. Making the decision to move a case from one logic to the other puts pressure on the caseworker to justify that this move is correct and desirable (Backe-Hansen, 2003/4).Cases with visible signs of maltreatment, violence and abuse tend to force a decision (Christiansen and Anderssen, 2010;Dubowitz, 2007;McSherry, 2007). By contrast, cases without clear evidence tend to linger in the system. In an interview study of 83 social workers who had recently made decisions regarding out-of-home care, Christiansen and Anderssen (2010) pointed to the caseworkers' reluctance to make decisions for placement when lacking conclusive evidence. Their study suggests that without the dramaturgy of the more obvious