This chapter provides a thorough examination of the neuropsychological assessment of competency to stand trial (CST), exploring the criteria, procedures, and difficulties involved in determining a person’s capacity to engage in court proceedings. Through an examination of clinical procedures and legal precedents, the authors give readers an idea of the criteria used to determine CST and the role of neuropsychologists in conducting forensic evaluations of competency. The chapter examines the neuropsychological concepts that underlie competency, such as reasoning ability, factual comprehension of court procedures, and cognitive talents. It also looks at the tools and techniques used in CST exams, such as cognitive tests, structured interviews, and specific tests meant to gauge a candidate’s legal knowledge and reasoning skills. Case studies demonstrate the usefulness of neuropsychological assessments in CST determinations, emphasizing the subtleties and complexity of evaluating competency in people with varying neurological profiles. Key takeaways include a better understanding of how cross-disciplinary CST exams are and how important it is to include neuropsychological information in legal evaluations so that cases involving competency issues are handled fairly and equally.