Critical discourse analysis (CDA) is known for its capacity to reveal ideology reproduced through discourse, but when applied to educational research, its focus on mere language constrains its utility for understanding and improving social reality. In this paper, through the example of a textbook study, we explore how CDA can be strengthened by critical realism. As a theory of ontology and epistemology, critical realism seeks to explain how causal mechanisms in society constrain and enable the emergence of human agency. As a practical framework, it can offer a research design for the textbook study, featured by a stratified ontology, a dialectic epistemology and a methodological requirement for self-reflexivity. Such a design can overcome the limitations of positivism and interpretivism. It can enable CDA to demonstrate both criticalness and a higher level of explanatory power, with the potential to identify real (rather than Utopian) possibilities for human emancipation.