In our day, leaders involved in ingenious sustainable development projects plan spaces and implement practices that are beneficial to the environment. These initiatives represent a fertile source of information on the competences linked to environmental design that we should nurture in our students. In view of improving our understanding of the competences that should be developed in environmental education (EE), this study sought to identify the competences used by leaders who participated in five sustainable development projects (in sustainable urban planning and forestry). The analysis of documents and data from individual interviews revealed that the main competences (cognitive, social and affective) used by the leaders interviewed, depended on creative, complex, flexible, longitudinal, adapted, patient, collaborative, humanistic and environmental planning. Finally, this study, of which we present the effects on EE, shows that leaders use competences which are associated with creative individuals.