New systems that seek to evaluate teachers with regard to their classroom quality often rely on observation instruments that capture general instructional pedagogies. However, decades of research suggest that content-specific dimensions of instruction also are important to differentiate teachers and improve student outcomes. We explore the degree of overlap between a general and a content-specific instrument when capturing upper elementary teachers' mathematics instruction. To do so, we conducted exploratory and confirmatory factor analyses on data from more than 2,000 videotaped lessons scored using both the Classroom Assessment Scoring System, a general instrument, and the Mathematical Quality of Instruction, a content-specific instrument. Findings indicate that there is some overlap between instruments but that preferred factor structures include both general and content-specific practices.