Participation in citizen science, a research approach in which nonscientists take part in performing research, is a growing practice in schools. A main premise in school-based citizen science is that through their participation, students and teachers make meaningful contributions to the advancement of science. However, such initiatives may encounter difficulties in drawing on students' and teachers' knowledge and incorporating their voice in research processes and outcomes, partly due to established knowledge hierarchies in both science and schools. This research theoretically examines misuses of students' and teachers' knowledge in school-based citizen science that can be defined as an epistemic injustice. This term describes wrongful evaluations and considerations of people's knowledge or perspectives. Based on existing theoretical work on epistemic injustice, we first map out epistemic justifications for public participation in science and discuss deficiencies in current forms of citizen science that lead to the perseverance of epistemic injustice. Then, we identify and characterize four forms through which epistemic injustice may be manifested in school-based citizen science. Our theoretical analysis is complemented by illustrative examples from citizen science projects enacted in schools, demonstrating cases where epistemic injustice toward students and teachers was either instigated or mitigated. We discuss implications toward educational goals and the design of school-based citizen science, suggesting that epistemic injustice can be reduced or avoided by delegating authorities to schools, maximizing teacher and student agency, and leveraging schools' community connections. Overall, this research establishes theoretical grounds for examinations of epistemic injustice in school-based citizen science.