This paper presents the framework of an intensive programme (IP) organised by UNESCO and addressed to young graduate professionals to prepare them for a career in fields related to sustainability. The aims of the IP were to address participants' environmental awareness and to develop attitudes and skills related to environmental planning and management. This paper focuses on the methodological aspects of the educational activities and on the setting in which the activities were delivered. Teaching methods based on a learner-centred approach were used in the training. During the activities, 17 participants were provided the opportunity to experience various aspects of environmental integration and sustainability principles in key sectors of planning procedures in the Lonjsko Polje Nature Park (Croatia). The activities were evaluated using quantitative and qualitative tools such as the environmental education questionnaire, the training quality and involvement questionnaire and two focus groups with participants. The results showed the relevance of the setting and the methods applied to develop environmental awareness and skills related to managing sustainability issues. Implications for future research about educational programmes based on the development of sustainability principles are discussed.