Under the global trend of competence-based approach to the training of psychologists, there is a lack of a feasible, valid, and reliable competency rating scale among psychologist training institutes in Taiwan. The purpose of the study was to construct an objective rating scale to be used in assessing general psychologist’s professional competencies by educators, clinical supervisors, and psychologiststhemselves. The rating scale was based on competency benchmarks developed by Lin and Huang (2013), and was constructed and used as the research instrument. A total of 297 counseling and clinical psychologists (including psychology interns) in various developmental stages were recruited as research participants. The results of the study showed that the scale has a high level of internal consistency as indicated by full scale’s and subscales’ alphas being greater than .93. A structural equation modeling analysis was conducted to test the construct validity of the scale. The six-factor model was found to be a good fit. The scale is comprised of six competences: assessment, diagnosis, and conceptualization; intervention; consultation; research and evaluation; supervision; and management. The study also showed that there were significant mean differences on the full scale and 6 subscales scores between doctoral level and master’s level psychologists; and between senior and junior psychologists. This result indicated that the scale has a good differential validity. Percentile rank norms were established for easy interpretation of the scores. Suggestions for practical applications and future study based on the current study results were also presented.