Teachers' classroom behaviors and their effects on student learning have received significant attention from educators, because the quality of instruction is a critical factor closely tied to students' learning experiences. Based on a theoretical model conceptualizing the quality of instruction, this study examined the characteristics of instructional quality represented by cognitive activation, student-oriented teacher behavior, class management, and learning support and investigated the relationships between instructional quality and students' affective and cognitive outcomes. The PISA 2012 survey, administered to students in Korea and Singapore, was used to conduct a latent profile analysis and structural equation modeling. It was found that using more student-oriented instruction and less strategies of cognitive activation was positively associated with lower performance in math, while well-managed classroom and learning support were positively associated with higher performance. The level of instructional quality was generally higher for Singapore than Korea in every index at all achievement levels. Most affective characteristics and the math teachers' instructional focus were positively associated with higher profiles of instructional quality. However, discrepant results were found between the two countries: Cognitive activation had positive effects on interest and self-concept in math as well as math performance for Korean students, whereas it only had a positive effect on math performance for Singaporean students. In contrast, student-oriented instruction had negative effects on interest in math as well as math performance in Korea, but a positive effect on interest in math in Singapore. The implications of each finding were discussed in detail.