This study examined the individual, class, and school level variability of the students' science achievement. It was hypothesized that there are school or teacher effects which contribute toward explaining achievement differences, besides the student level differences. Owing to the nested structure of the data in Trends in International Mathematics and Science Study, we used the Hierarchical Linear Modeling methodology. Besides the significant effect of engagement, the teachers' teaching certification in science and the topic coverage were both significant factors as were the effect of school SES and availability of remedial and enrichment programs in science. The study makes a contribution to a better understanding of the opportunity to learn variables at classroom and school level in students' science achievement.