According to environmental education scholars, most people do not use their environmental awareness to behave proenvironmentally. Scholars therefore believe that there is a gap between humans‟ cognitive and behavioural patterns. On one hand, a plethora of factors, such as religion, culture, self-efficacy, emotions, and so on, may be responsible for this gap. On the other hand, the ways we try to create environmental awareness may be problematic. The present study addresses the latter issue. Instead of conveying shallow environmental information, we foresaw that an action-oriented program would provide fruitful conclusions. To this end, the aim of this study was to examine the effectiveness of a project-based learning environment as an action-oriented method for developing proenvironmental behaviours. 33 student teachers, who took project-based Environmental Science course, in the 3rd year of Elementary Science Teacher Training Program at Ahi Evran University, Turkey, voluntarily participated in the present study and responded the questionnaires. A mixed design with quantitative and qualitative methods was used for the data analysis. The qualitative part consisted of a questionnaire including two open-ended questions. Content analysis was employed to examine these data. In the quantitative analyses, descriptive statistics, t-tests, and ANOVA were used. The findings of present study suggest that the project-based learning environment caused positive changes in student teachers‟ behaviours regarding environmental protection. The paper concludes with a discussion about the relationships between environmental education and science, socio-cultural issues, and educational implications.