In this concluding chapter, the concept of professionalization is first applied to environmental psychology. In addition to professional political work, the training of environmental psychological competencies is necessary for further professionalization. They serve to professionally fulfill the numerous design tasks of environmental psychology. Particularly important competencies are thinking in complex, systemic contexts and methodological competence. Part of the methodological competence is the verification and guarantee of the effectiveness of interventions through evaluation research. Most environmental psychologists still work in research-related areas, but the demand for environmental psychological expertise in practice is increasing. The evidence that environmental psychological interventions are effective, and the increasing demand for environmental psychological expertise, strengthen the demands for further expansion of environmental psychological education.