To improve environmental conservation efforts in Nigeria, environmental education content and practice need to be transformed to enable learners to study their own environments, share their knowledge, and generate conservation solutions. To achieve this, ten teachers, one researcher, and one educational technologist/research assistant engaged in a participatory action research study -- the Decolonising Environmental Education Pedagogy (DEEP) Project -- where curriculum materials were critically analysed to identify colonising elements, and a decolonisation model was created and implemented. Postcolonial theory explained colonised education while critical consciousness theory was employed for its transformation. The main research questions were: (i) What are the colonising elements and methods of Nigeria's environmental education? (ii) What are teachers' perceptions of the colonising elements and methods of Nigeria's environmental education and what are their envisions for decolonized environmental education? (iii) To what extent will a model generated in a participatory action research be effective for decolonising Nigeria's environmental education? Data included government-recommended textbooks, teachers' lesson plans, video-recorded participatory action research meetings (also referred to as focus group meetings), video-recorded lesson observations and field notes, and audio-recorded interviews. The DEEP project's main findings were (i) contextless, nonindigenous, and westernised content contribute to colonised education, while teacher-centred learning, student distrust, belief in Western superiority, field trip ban, time constraints, and emphasis on standardized examinations preserve the colonised environmental education, (ii) teachers became more aware of the colonised environmental education as they developed critical consciousness that spurred them to create a decolonisation model to transform their lessons, and (iii) the decolonisation model for transforming colonised lessons is effective to some extent. These findings have potential implications for education reform in contexts beyond Nigeria and environmental education. They could inform education reform in varied disciplines, other countries of the developing world, and also the disadvantaged communities in the U.S. and other developed nations, where disenfranchised sub-populations are taught to alienate their particular condition from environmental learning and, instead, forced to adopt a globalist perspective. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]