The last several decades have seen a major upswing in the development and use of psychological assessment instruments in forensic and correctional settings. At the same time, admissibility standards increasingly have stressed the importance of the reliability and validity of evidence in legal proceedings. Recent research has, however, raised serious concerns about (a) the reliability of forensic science evidence in general, (b) the replicability of psychological research findings in general and in field settings especially, and (c) the interrater reliability and predictive validity of forensic psychological assessment evidence in particular. In this introduction to the special issue of Psychological Assessment on the field utility of forensic assessment instruments and procedures, we provide an overview of key issues bearing on field studies, focusing on why such research is critically important to improving the quality of the practice of forensic mental health assessments. We also identify various methodological issues and constraints relevant to conducting research outside of controlled settings. We conclude with recommendations for how future field research can improve upon the current state of the discipline in forensic mental health assessment.