Research Findings: The purpose of the current study was to evaluate the structural validity of scores on a measure of global classroom quality, the Classroom Assessment Scoring System (CLASS K-3; Pianta, La Paro, & Hamre, 2008). Using observational data from a sample of 417 kindergarten classrooms from the southern and mid-Atlantic regions of the United States, we used confirmatory factor analysis to examine the structural validity of the CLASS K-3. Factor analytic findings supported a 3-factor and 10-dimension structure for the CLASS K-3; however, some modifications were made to the original CLASS model. Practice or Policy: Although the overall structure of the CLASS has been generally consistent across validation studies, some facets of the model may be less stable than others. Additional examination of alternative factor structures is needed to further clarify the relationships among the CLASS dimensions and domains. Current psychometric evidence provides support for continued use of the CLASS to guide intervention, instruction, and professional development.