Self-reports and questionnaires can be used by qualified evaluators who conduct assessments for the criminal justice system. These evaluators are expected to employ objective, reliable, and valid self-reports and questionnaires that meet rigorous test development and scientific standards. The purpose of assessments for the criminal justice system is to aid triers of fact (e.g., judge, jury) in responding to specific legal questions. Legal questions typically involve the evaluation of competencies (e.g., competency to stand trial [CST]); criminal responsibility (e.g., mental state at the time of the offense); and sentencing, parole, or release (e.g., dangerousness). Although self-reports and questionnaires offer a number of advantages, they also have limitations that may compromise their validity. This entry addresses the value and limitations of self-reports and questionnaires and then ...