Especially schools in disadvantaged areas have to face serious challenging circumstances caused by external conditions: low students' basic learning skills, unfavourable socioeconomic background, insufficient parental support (Muijs et al, 2004; Teddlie, Stringfield, & Reynolds (2000). The relevance of the socioeconomic composition of the student body for educational success has been proven in several studies (Baumert, Stanat & Watermann 2006). Beyond that we can identify unfavourable internal factors in schools that don’t exhaust their potentials: poor learning culture, low support for learning, inadequate leadership practices or insufficient teacher engagement (Muijs et al, 2004). Considering the external context the success of schools can be estimated as expected or as unexpected (Holtappels 2008). Studies show unexpected effective schools, where students attain high achievement although the social context show unfavourable conditions for successful pedagogical work. Therefore the development of the internal organisation and the culture of learning and building capacity of change are the main focuses for improving schools and to enhance the educational quality on class and school level (Harris & Chapman 2004). The paper follows three research questions: 1) What kind of school types are to identify based on relationship between student outcomes and context conditions? 2) Are there differences between unexpected effective and ineffective schools in challenging circumstances by considering characteristics of the school quality on school and classroom level? 3) Are there different types of teachers with specific patterns, e.g. regarding to teacher collaboration or teaching quality features, which vary significantly between the groups of schools? The research is embedded in the study Developing Potentials – Empowering Schools with 36 secondary schools in the Ruhr Metropolis of Germany. Data about external and internal features of school are based on questionnaires with principals, teachers, students and parents. Reliable scales could be adapted or new ones were composed. On the first step we use analysis of variance and mean comparison tests to identify global differences between the school groups in high and less privileged areas with unexpected high and low student achievement regarding to various characteristics of school quality (e.g. teaching quality, teacher collaboration, leadership practice). On the second step latent class analysis is applied, in order to find out specific patterns of teachers` behavior by comparison of school types. Furthermore we can follow assumptions about relationships between school quality and teacher factors by using structure equation models.

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