Background: Quality in early care and education (ECE) has been widely studied across several decades, though there is not a single standard definition of quality across ECE contexts. Classroom quality often encompasses both structural and process features of quality. Teachers are often not included in discussions about quality in ECE programs despite their role in implementing ECE policies and regulations. Objective: This study used an explanatory sequential mixed methods approach to understand teachers' perceptions of classroom quality in Head Start. Methods: A convenience sample of center-based Head Start teachers in the mid-Atlantic United States participated in an electronic survey (n = 48) and semi-structured interviews (n = 10). Results: Our quantitative results suggest that teachers perceived teacher-, structural-, process-, and center-level indicators of quality as being important for overall classroom quality. However, our qualitative results provide more nuanced information about how teachers define quality, such as specifying teacher-child ratios that would promote high-quality instruction. Our integrated mixed methods findings identify areas of alignment and misalignment between the quantitative and qualitative results, with teachers prioritizing structural and process indicators of quality in both phases of the study. Conclusions: These findings highlight the need to review and revise ECE standards to reflect the experiences of our current ECE workforce.