Within the first year of the Secondary Teacher Training Environmental Education Project (St[superscript 2]eep) in Zimbabwe, project stakeholders, including lecturers, college administrators, local project coordinators, and donor representatives, expressed concern about the non-sustainability of the project due to its over-reliance on its international donor. In response to this challenge, a process of critical self-reflection through self-assessment workshops was started to give an opportunity for key project stakeholders to explore the challenge of project sustainability. Applying the principles of expansive learning theory to St[superscript 2]eep's reflection processes, this paper shows how the contradictions that emerge from the interaction between different project stakeholders can be powerful sources for learning. This has resulted in new forms of activity to address the challenge of project sustainability in St[superscript 2]eep. The insights of this paper may be useful for other donor-funded environmental education projects that are confronted with the challenge of project sustainability. (Contains 1 note and 5 tables.)