Case conceptualization is a foundation of cognitive-behavioural therapy (CBT) because it describes and explains clients' presentations in ways that inform interventions. Yet the evidence base challenges the claimed benefits of case conceptualization. This paper reviews the rationale and evidence base for case conceptualization and outlines a new approach that uses the metaphor of a case conceptualization crucible in which a client's particular history, experience and strengths are synthesized with theory and research to produce an original and unique account of clients' presenting issues. The crucible metaphor illustrates three key defining principles of case conceptualization. First, heat drives chemical reactions in a crucible. In our model, collaborative empiricism between therapist and client provides the heat. Second, like the chemical reaction in a crucible, conceptualization develops over time. Typically, it begins at more descriptive levels, later a conceptualization incorporates explanatory elements and, if necessary, it develops further to include a longitudinal explanation of how pre-disposing and protective factors influence client issues. Finally, new substances formed in a crucible are dependent on the chemical characteristics of the materials put into it. Rather than simply look at client problems, our model incorporates client strengths at every stage of the conceptualization process to more effectively alleviate client distress and promote resilience.