By sampling extreme cases (five high-performing schools and five low-performing ones), the researcher revealed the differences in the teachers' motivation (Mattar, 2010) as well as the extent to which Principals adopted the instructional leadership style (Mattar, 2012) in the two sets of schools. Here, she looked for additional issues, within the same sample, that make a school a high-achieving one or a low-performing one. Factors affecting school performance are: students' SES and their quality, teachers' quality (their ability and the quality of work life) and the way they are motivated, the Principal's leadership style, and the schools' physical working conditions. (Contains 5 tables.)