As environmental and sustainability issues are becoming embedded in the school curriculum, there is a need to understand how environmental identity develops within the complex social structure of the classroom. Reflection is a potentially valuable classroom process to consider as it intersects student learning, identity work, and agency. This embedded qualitative case study explored how three elementary students from a school in British Columbia, Canada, reflected on their experiences during an in-school program focused on the issue of marine pollution. Analysis of student focus group transcripts and journal entries found evidence of inquiry reflection, emotional reflection, and critical reflection on the facilitated environmental action. These appeared to play different roles in supporting a student's ability to connect their experiences in the program to the curriculum and/or their developing environmental identities. An individually reflective lens, however, taken by students to critically self-reflect on how their own actions might contribute to the issue of marine pollution appeared to be challenging for them. Five strategies are offered to educators to support the design of activities that might foster environmental identity development (EID) in the classroom through inquiry reflection, emotional reflection, critical reflection, and self-reflection.