The purpose of the current study was to evaluate the structural validity and stability of scores on a measure of global classroom quality, the Classroom Assessment Scoring System, Kindergarten-Third Grade (CLASS K-3; Pianta, La Paro, & Hamre, 2008). Using data from a sample of 417 kindergarten classrooms in the rural Southern and Mid-Atlantic regions of the United States, confirmatory factor analysis was used to determine the structural validity of CLASS K-3. Factor analytic findings supported a 3-factor and 10-dimension structure for the CLASS K-3; however, modifications were made to the original CLASS model. In addition, stability of CLASS scores was assessed through intraclass correlations with a subset of classrooms (n = 30). Results indicated that the Emotional Support and Classroom Organization domains demonstrated higher levels of 1-year stability than the Instructional Support domain, with Positive Climate being the most consistent dimension. Finally, hierarchical multiple regression was used to determine if professional development and classroom resources positively predicted CLASS K-3 scores. Regression analyses did not yield a statistically significant relationship between professional development and CLASS K-3 scores, and though the relationship between classroom resource variables and CLASS scores displayed statistical significance, the magnitude of effect was consistently negligible. [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://www.proquest.com/en-US/products/dissertations/individuals.shtml.]