Global environmental issues are increasing due to the rapid developments in science and technology. To address these environmental issues there is a need to create an awareness about environmental education among the masses. This can only be possible through teachers and teacher educators. My underlying assumption is that science teachers are teaching environmental concepts as scientific facts, without creating an awareness about environmental education. The ultimate purpose of this study was to explore the beliefs of a secondary science teacher about environmental education and how his stated beliefs matched with his classroom practices. The study was conducted in one of the co-operative schools of the Aga Khan University- Institute for Educational Development, in Karachi Pakistan. And the sample for this study included one secondary science teacher. The research design was qualitative, which included multimethods. The methods included semi-structured interviews, classroom observations, pre-post conferences, document analysis and the teacher's teaching/learning stories. The study employed different data collection tools such as interview guidelines, a classroom observation checklist, teaching/learning stories and pre-post conference guideline questions. The findings of the study suggest that the participant science teacher in this sample believed in teaching environmental education in a science classroom. He also believed that students should be given a free choice to be involved in environmental participatory activities such as environmental management projects in the real environment. However his enacted teacher centred classroom practice was contrary to his stated beliefs. The factors that prevented him from enacting his beliefs were identified as his content knowledge, pedagogical knowledge and support from the administration. The study thus suggests professional development programmes and workshops for that employ reflective practices. Moreover, constructivist approaches should be designed to help teachers to enhance their content, pedagogical content knowledge about environmental education, and that should develop them professionally.