This portfolio explored issues that are relevant to the judgements routinely made by clinical psychologists. The first chapter provides a theoretical overview of relevant issues. In this chapter, firstly, the debate over the relative merits of ‘clinical’ and ‘statistical’ approaches to clinical judgement (Meehl, 1954) is reviewed. It is noted that, although much of the empirical evidence supports the greater accuracy of statistical approaches to making judgements (where appropriate methods exist), they are rarely routinely used, and clinical approaches to making judgements continue to dominate in the majority of clinical settings. Secondly, common sources of errors in clinical judgement are reviewed. These include the misuse of cognitive heuristics, the presence of clinicians’ biases, the limitations to human information-processing capacities and the over-reliance on clinical interviews. Finally, some of the basic strategies that can be useful to clinicians in improving the accuracy of clinical judgement are described. These include undertaking advanced level training programs, using quality instruments and procedures, being wary of over-reliance on theories, adhering to the scientist-practitioner approach and being selective in the distribution of professional efforts and time. In the subsequent chapters these strategies are explored further through four clinical case studies. These cases were collected during the university placement program and they have been selected to illustrate some of the approaches as clinician may use in attempting to optimise the accuracy of judgements necessary in the context of clinical psychological practice. The final chapter provides a brief overview and discussion of these cases in relation to the issues identified in Chapter One,