This study utilized a quantitative research approach with a survey design to determine whether a sample of K-8 principals in the state of Illinois, that rated teachers in a set of classroom instructional videos, exhibited inter-rater reliability since they all received the Illinois state-approved training and certification for teacher evaluators. K-8 principals were surveyed and asked to watch three videos, that demonstrated teaching from a kindergarten teacher, a fourth-grade teacher, and a middle school teacher, and record evidence to be used to rate the teacher on the Danielson Framework for Teaching rubric. Scores were examined and analyzed using an intraclass correlation coefficient (ICC) to determine the extent of inter-rater reliability present. The researcher also looked for patterns of leniency and other trends relating to the participants' demographic information and level of experience. The study also explored how the K-8 principals use yearly teacher evaluation data. The study found that inter-rater reliability exists in the overall ratings of K-8 principals. Some small pockets of statistically significant differences in ratings were found when principal background information was compared, but there were more similarities than differences. The study found that there are factors that influence a principal's rating of a teacher, which may result in leniency in some ratings. Furthermore, most principals did indicate using the yearly evaluation data for professional development opportunities for teachers, as was a goal of Danielson in the creation of the framework. Finally, the type of training that the K-8 principals completed to become a certified teacher evaluator did not impact the reliability of the teacher ratings in the videos, nor did the ability of the principal to pass the certification exam the first time or not. [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.]