This quantitative, non-experimental study explored the differences between principals' perceived level of influence evaluation barriers have on the accuracy of teacher evaluations. A self-administered questionnaire was used to collect data from Montana principals regarding their perceptions of: (a) teacher performance combinations (b) the strength of influence selected barriers have on the accuracy of teacher evaluations principals provide teachers, and (c) demographic information. Participating Montana principals were asked to categorize the teachers they supervise into four performance combinations: (1) Good Teacher/Good Employee or (GT/GE), (2) Good Teacher/Marginal Employee or (GT/ME), (3) Marginal Teacher/Good Employee or (MT/GE), and (4) Marginal Teacher/Marginal Employee or (MT/ME). Principals then used an 11-point Thurstone scale to estimate the influence eleven evaluation barriers (Board, Community, Conflict, Expectations, Process, Staff, Standards, Superiors, Time, and Training, Union) had on the accuracy of teacher evaluations. A 4 X 11 factorial design was used to explore differences between principals' perceived influence of selected evaluation barriers for different teacher performance categories, and a 10 X 11 factorial design to explore the differences between barriers. A one-way between groups ANOVA was used to identify any statistically significant mean differences and a post-hoc Tukey HSD test was used to determine the magnitude of the mean differences. The results this study identified the percentages of performance combination distribution as: 6% MT/ME, 11% MT/GE, 11% GT/ME, and 72% GT/GE. The evaluation barriers were found to have hierarchical levels of influence on the accuracy of teacher evaluations principals provide teachers: (1) Dominant Barriers (Expectations, Time, Process, Union) have higher levels of influence, (2) Mixed Moderate Barriers (Standards, Staff, Training) have indeterminate levels of influence, and (3) Subordinate Barriers (Conflict, Community, Superiors, Board) have lower levels of influence. Three performance combinations were identified as challenging when differentiating performance: (1) (GT/GE & MT/GE) influenced by the evaluation barrier Conflict, (2) (GT/GE & GT/ME) influenced by the evaluation barrier Conflict, and (3) (GT/GE & MT/ME) influenced by the evaluation barriers "Conflict," "Union," "Time," and "Staff." [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.]