The Child Welfare and Protection Board (CP), which plays a central role in Dutch child welfare is an agency of the Dutch Ministry of Justice. The CP may present petitions to the juvenile court for their judgement regarding the custody or guardianship of children. The Board presents petitions concerning legal propositions for custody, suspension of the execution of custody, provisional guardianship, and dispossession and restriction of custody. These petitions are based on an investigation of the social conditions of the child and the family. In the past, the quality of these investigations has often been questioned, the main criticism being the lack of any systematic procedure and the strong intrusion of personal opinion. Nevertheless, social workers of the CP Board often regarded potential changes to these investigations with some apprehension because they feared the assessment procedures might lose their human character. More recently, the CP Board has experimented with a system of testing hypotheses in its assessment procedures. In this article, we present the results of an evaluation of this new procedure. The results are presented in the context of the recent debate, published in the British Journal of Social Work , between the advocates and opponents of making social work more scientifically rigorous.