The understanding of personality and abnormal behavior has been of interest to scholars since before 3000 BC. The view that human character could be successfully studied through careful observation and experimentation emerged in the late nineteenth century. Efforts to understand personality and cognitive processes can be found in the work of several pioneer psychologists and psychiatrists who attempted to understand and treat mental disorders. Prior to World War I, some governments developed ideas about important attributes to be evaluated in applicants for military pilots in order to understand personality qualities needed for the job; however, there were no standardized assessment techniques developed for personality assessment. Two major assessment approaches were published shortly after World War I: the first self-report personality questionnaire for addressing symptoms of maladjustment, and the Rorschach inkblot test for personality appraisal. This chapter provides information about the need for understanding personality in screening military personnel during World War II. A broad range of new personality tests are described and recent contemporary controversies in personality evaluation methods that have occurred with two of the most widely used measures, the Rorschach and the MMPI instruments. The impact of these recent efforts will likely define in what directions future personality assessment will go.