The Performance Assessment and Evaluation System (PAES) is used by all major universities in the state of Utah to measure the effective teaching skills of preservice candidates as they progress through their teaching preparation program. The resulting ratings are used to make high-stakes decisions relating to course completion as well as recommendation for licensure. This study analyzes the factor structure and tests for measurement invariance of PAES ratings assigned to 663 elementary education candidates at Brigham Young University across two measurement occasions. The candidates were rated by 30 clinical faculty associates. This study also examines the degree to which differential rater effects impact the PAES ratings of these candidates. A bifactor model, with a general factor measuring effective teaching skills measured through observation, and a specific factor measuring effective teaching skills evaluated through conversation best fit the model. Evidence of measurement invariance was found between evaluations completed for Practicum 1 and Practicum 2 candidates. This study also found that differential rater effects impact the PAES ratings of individual candidates, indicating that a candidate's rating may depend on which rater completed the evaluation. Similar research studies should be conducted to analyze the quality of PAES ratings of teacher candidates in the various secondary education programs at BYU. In addition, since the PAES is used at other teacher preparation colleges and universities in Utah, similar research studies should be conducted to examine the quality of PAES ratings of teacher candidates at these other institutions. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]