The authors provide guidelines for the forensic assessment of psychological injuries to inform decision-making in the legal system (e.g., tort litigation, disability determination). An evidence-based approach is described for determining the onset, causation, course, amelioration, and prognosis of psychological injuries. The purpose of the assessment is to evaluate a plaintiff seeking financial compensation for emotional distress, functional impairments, and possible treatment costs alleged to have been caused by a defendant. The authors discuss the use of multiple measures and methods, the assessment of malingering, exaggeration and feigning and issues in diagnostic classification. Differences between the DSM-5-TR and ICD-11, dimensional approaches to assessing psychopathology, the assessment of functional impairments, examiner bias, cultural considerations and tele-assessment. The authors illustrate their multimethod approach with a case example of a plaintiff who alleged a psychological injury following a motor vehicle accident (MVA). The assessment of malingering, exaggeration and feigning is illustrated with the MMPI-3, Personality Assessment Inventory and the Inventory of Problems-29. In the case example test results are discussed from the Rorschach Performance Assessment System and the World Health Organization Disability Assessment System. Structured Interview results from the SCID-5 and ADIS-5 are discussed. Future directions include the development of precision health and personalized approaches to assessment and treatment planning.