The authors present a vision of the school as an environment tailored to the developmental needs of students and teachers. They argue that only such an environment creates conditions promoting the achievement of the goal of the twenty-first century education, i.e. a gradual approximation of children’s functions to the mature behavior of an adult. Furthermore, the article describes the key elements of the school functioning as an organization fl exibly adapting its structure and actions to the dynamic developmental situation of students and teachers. In the last part of the text, the authors defi ne the necessary competencies of teachers as those who constitute the core of such an organization.