Finding effective methods for improving teaching quality is crucial because it has been found to be the most important factor in education. This paper compares two approaches of improving teaching quality through a one-year experimental study involving two experimental groups and one control group. The first is the use of education standards and the second is the use of education standards combined with a teacher development program. Teaching quality was measured in four variables: Building classroom as a learning environment (CLE), instruction, questioning, and orientation. In this study, 1255 students and 45 teachers from 43 junior secondary schools in two provinces of Indonesia voluntarily participated. Multilevel modelling was employed and the results indicate that both interventions have significant effects on the outcomes. However, as expected, the second intervention is significant in all variables and has larger effects, whereas the first intervention is significant only in two variables: CLE and questioning. The findings of this research imply the need to have clear and concrete education standards and to enhance these education standards with training sessions to facilitate better teaching quality.