This article describes and compares uses and functions of the formulation-decision pair in three types of diagnostic interviews. The typically medical INVESTIGATORY type contains no formulations. In the EXPLORATORY type, which typically occurs in psychiatric interviews, the formulation-decision pair is used for exploring the patient's experiences. In the COLLABORATIVE type, typically found in psychotherapy, the interviewer uses the formulation-decision pair for translating the patient's troubles into a professional problem definition, thus initiating the patient's protoprofessionalization.