This paper investigates engagement (E), alignment (A), and rigor (R) as vital signs of high-quality teacher instruction as measured by the EAR Classroom Visit Protocol, designed by the Institute for Research and Reform in Education (IRRE). Findings indicated that both school leaders and outside raters could learn to score the protocol with adequate reliability. Using observations of 33 English language arts (ELA) teachers and 25 mathematics teachers from four high schools, findings indicated that engagement, alignment, and rigor were all predictive of math and ELA standardized achievement test scores when controlling for the previous year's scores, although some of the associations were marginal. Students' self-reports of their engagement in school were also generally predictive of test scores in models that included perceived academic competence and observed engagement, alignment, or rigor. We discuss the importance of classroom engagement, alignment, and rigor as markers of instructional quality and the utility of the EAR Protocol as a means of assessing instructional quality.