The cross-sectional study conducted here evaluates for the first time whether schools can successfully transform themselves into so-called "problem-solving" organizational units independently, as demanded by education policy, in order to continuously develop their teaching within the framework of school development. The results of this study primarily call into question the sustainability of school development, as neither the teaching staff nor the school leadership members at the evaluated vocational schools believed that school development had any impact on teaching and the professional skills of individual teachers. This result is partly justified by the implementation strategy adopted by the schools. Generally, the teaching staff is insufficiently involved in decision-making processes and, for example, is inadequately informed about the degree of goal achievement and measures of completed school development projects.