The purpose of this study was to examine the current diagnostic standards and assessment practices when diagnosing Post Traumatic Stress Disorder (PTSD). This study used a web-based survey to gather information on opinions and assessment practices of psychologists who were licensed with no board-certification, board-certified in clinical psychology, or board-certified in forensic psychology. Significant differences were found between the three groups of psychologists in frequency of inclusion of DSM-IV-TR Criterion A, in use of recommended collateral information sources, in recommended domains assessed for when conducting a differential diagnosis, in use of assessment methods or types of recommended instruments, in conducting post-assessment interviews, in assessing for over-reported PTSD symptoms, in number of recommended detection strategies for over-reported PTSD symptoms, and in use of recommended assessment instruments for over-reported PTSD symptoms in PTSD diagnosis. Effect sizes for significant differences ranged from medium to large, indicating that boardcertification status has a significant impact on psychologists’ diagnostic standards and assessment practices related to PTSD. Overall results support literature on general practices and current opinions related to PTSD diagnosis. Overall results and findings are discussed in the context of previous literature and recommended standardized procedures of PTSD diagnosis. Implications for future study are offered.