This chapter discusses the rationale and main features of the Dynamic Approach (DA) to teacher and school improvement. It is argued that this approach to teacher and school improvement is based on the dynamic theory of educational effectiveness and thereby places emphasis on the quality of teaching and on the conditions created at different levels for improving the quality of teaching. Moreover, the DA stresses the importance of the school as a learning environment and identifies the factors that are important for improving the school learning environment (SLE) and which could be addressed by school improvement projects. The importance of a whole-school approach that uses a conceptual framework which specifies the factors related to the quality of teaching and the SLE is highlighted. In the second part of this chapter, we present the main steps of the DA and argue that these steps can be followed by stakeholders operating at different levels of the educational system, such as the classroom, the school and the context. This is due to the fact that in the dynamic model, the factors operating at different levels are linked and are also able to influence the quality of the SLE, of teaching, and of the learning and its outcomes. Finally, examples of school-based interventions which have taken place in different countries are given in this chapter to help readers understand how the DA has been put into practice to improve the quality of teaching and the SLE.